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Heads up on cheap generic drill press (DP)

Posted by on August 26, 2013

Not much of an article

Just a heads up for anyone about to buy a cheap / generic drill press (from Harbor Freight or similar) – Make absolutely sure you test it right out of the box at the store, do not take it home without doing so.

Here’s the reason why, they often lack QC or ship out defective units from China on purpose (as for instance the buyer may be requesting a cheaper version) — The primary problem you’ll encounter is massive play on the quill, due to an oversized hole on the body. I don’t know how they manage to do this while they bore them out, but I’ve encountered 2 out of 3 drill presses had this problem. We’re talking over 5MM play with the quill fully extended, using a 3MM drill bit and measuring at the end of drill bit itself.

This short video depicts quill play and vibration (there was so much vibration one of my tools fell to the ground)

 

Do not confuse a factory defect vs a lack of adjustment on the quill (most drill presses will have a set / grub screw with a lock nut that is used to prevent the quill from turning, it also applies a bit of force that further reduces play, but it’s not a gib). If it turns or feels sloppy on that particular axis, it could be the setscrew is loose. The problem with the faulty bodies will present at near the full extension of the quill, there you’ll be able to push it around to feel for slop.

The spindles are fairly straight, I’ve measured 0.08mm on the worst one and the current one I own has a bit under that, which is expected on a non precision machine and it’s actually plenty good for most uses. However the quill has about half a millimeter of play, this is the best unit I could get from what they had in stock (plus returning them takes time and money, so you gotta draw the line somewhere).

In my particular case I’ve found the spindle to be supported on multiple bearings and not a single bushing, which is in my opinion quite good despite the low quality of the bearings, at least they’re there.
 

Put it on vibrate!

The second issue is vibration, and this one is hard to isolate specially if you are at the store or you don’t have the right tools at home.

I don’t think you can fully remove vibration from these drill presses, there are inherit design flaws that cause resonances everywhere and the 50/60Hz motor doesn’t help with this either. The actual belt tensioner is the primary culprit, it will transmit every single vibration the motor encounters, down to the body of the drill press and onto every other component, traveling down the shaft and onto the base, which then propagates to your work table, etc, etc.

However, there are a few things we can do, one is to check that both pulleys are not only running true, but are also level in respect to each other. Then, we can inspect the belt — it will usually be a low grade belt, possibly stretched and deformed from all the time it spent tensioned in one position ever since it left the factory in China. I don’t know why they don’t just put the belt in a bag and tell you to install it (this would help a lot of people familiarize with the pulley system). I think we can blame lazy people for this one or the factory for shipping them out with tension.

Not to forget, the motor is mounted on 3 or 4 places (more often 3 than 4…) make sure the motor is perfectly vertical to thus obtain a perfectly horizontal drive pulley. The issue with the tensioning system they use is that it pivots on a sloppy make-shift hinge with over-sized holes and it’s usually all bent up from mishandling during shipping, etc. You have to double check everything.

If you hear a sort of “click, click, click” coming from the drill press it could be the spindle pulley that happens to be loose, make sure both pulleys are tight on the shafts and that they’re sitting on the slotted end. If it sounds along the lines of “clank, clank, clank” then it’s probably the belt rubbing against the housing.

For an old drill press, any sort of clicking noise could well indicate worn out bearings, specially if you subjected them to side loads.

 

To recap…

Don’t expect much from a cheap drill press, if you can, buy an old used one. The older, the better. Even if it’s a monster and you need 4 people to move it around, you’ll be investing in a tool that will far outlive you, vs a piece of Chinese crap that will make you waste your time and money. Not to say there aren’t “gems” within the “turds” but, make sure you double check everything before you commit to one of these lousy imports.

Don’t rely on brand names either, most of them are importing from China, sure some pay the extra for QC and are usually better in that regard, but you can still expect faulty motors and whatnot from your favorite brand names… So, bust out your tools and spend some time before you fully setup your new drill press.

Have fun.

 

 

 

Taking apart the CQ6123B Lathe – Part 2

Posted by on August 5, 2013

The journey continues…

We’ve taken apart the apron and most components of the lathe, but the motor still remains and some other aspects have to be addressed… Grab a cup of “something” and start reading!

 

Removing the motor

The motor on my lathe is a single phase capacitor start AC motor, it’s 1420RPM 3/4HP.
C1 is 100uF (starting cap), C2 is 12uF (running cap)
4.5A nominal current, model number is YL8014.

They sure rate it as 3/4HP, but it’s more like 1/2HP in reality.

 

Removing it is the hardest part I’ve encountered so far, because of how difficult to reach the lower mounts are.

If you want to remove it because it’s not working, make absolutely sure it’s not a simple capacitor fault. If you want to remove it for weight reasons or reassembly / inspection — keep reading!
To begin with you might want to remove both belts so the motor will be free to move away once the mounting nuts are released.

The motor is held by four nuts, the mounts are screwed onto the cast iron bed. Each nut has a lock washer and a washer, this is what makes it difficult to undo them at first, and due to how hard to reach the lower ones are (specially the lower one by the headstock) it might require some special tools or a dose of ingenuity.

At this point you have to ask yourself if you can lift the entire lathe up to get more clearance underneath the motor, or if you have the actual tools to reach without trouble.
To access the upper two nuts, you might want to remove the electrical box that sits on top of the motor, it’s held in place by three screws and you can read about how to remove it on the electrical portion of this lengthy guide.
The four nuts are 10mm, a combined wrench will do just fine for 2-3 of them, but like I said that last one is hell unless you lift the lathe up, if you do lift it make sure you lift both sides equally — you don’t want to stress the bed in any way.

Also, if you try to tilt the entire lathe to the side to gain more clearance by the motor, make sure you aren’t forcing the gearbox handle onto the table / box (wherever your lathe is) because you will snap it or bend it and that’ll be the end of it. If you plan to tilt the lathe, put the gearbox on the “1” position and lock it, if you removed the gearbox faceplate, use masking tape or string to keep the lever up by the 1st position (first gear to the left), otherwise try some wooden shims.
Once the four nuts, lock washers and washers are out, and assuming you took the belts off, the motor should slide right out. Before I did this however I made sure to undo the cable nut that goes from the motor to the electrical box, this way I was able to turn the box and gain a bit more clearance, plus we also avoid stressing the cable in any way by releasing tension.

To slide the motor off, I decided to support it on some scrap wood so I didn’t have to force myself with all it’s weight at once (and to prevent possible dissasters, plus I should not stress my wrists too much, so that’s another reason for this step).

And that’s all there is to the motor, in my case the fan protector (which is held by three small phillips screws) was all bent up and had been touched up with paint (it probably had rust and they covered it up). It was almost touching the fan, so I was forced to remove it and straighten it up. Of course, I also wet sanded and repainted it with black gloss, high temperature paint. (I would’ve use matte, but anything that will most likely catch oil and swarf should be slick as to not attract more crap).

The motor typically sits underneath the electrical box, and on top of it lies the swarf shield / cover, so not much dust or swarf goes on it, however some of it always finds it’s way into the motor fan.

Gearbox

It goes without saying that you should grease up the gears. Some people use motoroil instead and they pour it through the oiling ports, it works but it gets messy real fast. Either way, keep them lubricated and if you are not to use power-feed or threading operations, don’t leave the gearbox engaged.

When the gearbox is not engaged, the gears on the handle are still moving, they’re coupled to the drive-train, but by disengaging the gearbox you remove wear from the leadscrew mounts (there are no bushings or bearings, it just rolls on a cushion of oil against the polished cast iron)

Better models have a spindle gearbox, these often have a sump for the oil and are more complex, but the leadscrew is mounted and driven in almost the same way.

Electrics

The wiring is almost top notch, which is surprising but here’s the problem, the run and start capacitors for the AC motor are complete trash. So I highly recommend you replace them even before you decide to start turning metal. I of course turned for a few minutes during the inspection to make sure everything worked, but with the lathe as-is you should not use it due to lack of lubrication and proper setup.
Now, why replace the capacitors? because they won’t last very long at all and they will scare the crap out of you when they do fail short, they will also ruin your day if they fail open or fall so far off spec the motor just stalls and won’t even turn. Let me remind you, the motor costs a lot more than the two capacitors, so invest in a couple good caps and get it over with!

To remove the capacitors you’ll either need special low profile tools to reach the tiny 7mm nuts that hold the capacitor shields or, you’ll have to take the electrical box out (it’s held by three allen head screws, one of which is underneath in between the capacitors, so you’ll have to remove the right cap first to get to the allen).

Both capacitors are installed with twist-on wire nuts, which is fine.

The other lacking point on the wiring is the mains cord, it’s not even a 3×2.5mm which is the absolute minimum I would’ve used for these loads (specially the starting load, to prevent drop and thus excessive current draw) — So you may want to replace the power cord with a proper 3×2.5mm or 3x3mm.
Earth wise, no locking washer was placed on the allen screw and the paint was not cleaned off, so the only contact made was through the screw and not directly onto the body, which isn’t good. The torque on that screw was also very low, earth connections should be solid for safety reasons. So, address that as well once you reinstall the box.

The reverse switch is very small and flimsy, nothing like what you’d find on older lathes… But for now it’ll do, it’s actually a good quality unit as is the safety switch, but due to personal preferences you may want to replace these for something that makes you feel safer, for now I’ll keep them.

Lubrication

As stated, remove the shipping oil from all mating surfaces. Two safe chemicals are acetone and brake cleaner, I chose the former. The idea is to strip the shipping oil off and keep cleaning until no residues are left on the rag. Even at this stage, if you were to oil and reassemble, you’ll soon notice the oil becomes darkened after a few passes. This is due to friction of uneven surfaces “mating” together, but mostly due to residues still left in the metal that are being washed off by the machine oil. Steel and iron are porous metals, specially if cast. You can actually think of most metals as wood, for instance iron (ask any blacksmith) is fibrous and thus very similar to wood.

I use light machine oil for everything now. I don’t buy into the whole “you must use special way oil and special spindle oil and…” — Most people use motor oil, some even swear detergent or non detergent makes no difference when it comes to the ways of the lathe bed and other components. One issue with the viscosity of certain oils is how often you’ll have to lubricate the machine. Most of the gears are not under heavy load (unless you are knurling or performing heavy cutting operations with the power feed) but still I prefer to use lithium grease on the gears.

Speaking of viscosity, most “way oil” has additives in them such as a viscosity enhancer, the idea being it’ll stay in place for longer… problem is, it will also catch a lot of swarf and dust. I’d rather use light machine oil often and in excess, than use sticky oil that will ultimately make a mess and force me to spend time cleaning it up afterwards.

It’s all up to you, lubrication is like talking about religion or linux for that matter, everyone has a different opinion so it’s better if you experiment and come up with something that works for you and your lathe.

However I would like to add that some lathes have been around for over 100 years and they’ve always been oiled with regular motor oil (20w) So it all comes down to how well you take care of the lathe, not exactly which type or brand of oil you use. Because more often than not, you’ll fall into marketing traps and waste your money over nothing.

Lubrication on a lathe and any other equipment is akin to the lubrication on an internal combustion engine, it’s the life of the engine so don’t take it lightly either, make sure you absolutely cater to the requirements of your specific tool.

If you decide to use grease for the gears, try not to over-do it as it will not only sound like there’s a chewing monkey inside the lathe (or the lathe is chewing up a monkey?) but it will eventually make a sticky mess in there. You have to avoid oil and grease making contact with the belts to prevent slip under load (the friction causes heat and loss of material which in turn can easily shorten the life of the belt, specially if it’s under heavy tension).

 

Electrical improvements

No spindle tachometer was provided, but the electric box has a cutout right where the headstock is, and wouldn’t you know it, the headstock also has a cutout, so you could rather easily install a bracket with a hall effect switch and place a magnet on the outer portion of the spindle (2 gram magnet). Then use shielded wire and an insulated box for your own electronics. There’s plenty space in the original box, but you might want to run the low voltage portion on a separate box and just place a transformer or smps board inside the original box.

Another idea would be to add an SSR or figure out a way to interface with the original safety switch relay so that a micro-switch could be used on the bed to prevent the toolpost from running into the chuck. There would still be some momentum going after you turned the motor off, but at least it wouldn’t keep going until it either sheared a key, caused gear damage or worse. (chucks are not cheap!)

For a finer degree of speed control a VFD could be used, however the supplied motor has a centrifugal switch, so I’m not entirely sure how you’d interface a VFD to one of these. The other -not so cheap- alternative would be to replace the motor with a treadmill motor, which are ideal for this application, of course they require a separate driver but it should be worth it.

Mechanical improvements

Right off the get go you can see the belts are lacking, severely. Specially the V belt… it’s way too thin and it will slip if not break easily. I’ve read some people assume they’ve used a thin belt to “reduce vibrations” but that’s most likely marketing bs. Whatthey’ve done is reduce costs even further, as the older versions had a 3 times thicker belt and pulley system in there.

However, we can’t just replace the belt with a thicker one, we need to replace the pulleys… you could get away with two new pulleys but the drive train has three of them, one of which is slotted for the distribution belt. So it would be quite a task to reproduce it without a mill or an indexing setup. If you had a spare one you could part off the V pulley portion and turn a new one, then interference-fit it with loctite for good measure, keyed would be even better. I say “if you had a spare one” because I’m not too keen on modifying one-off parts.

Lots of play on the apron longitudinal feed, the shaft is not supported on both ends and none of them are mounted on ball bearings whatsoever, most don’t even have a bushing. So that’s something to think about and be concerned specially if you plan to use your lathe on a daily basis.

The banjo is rock solid, by this I mean it’s very hard to actually use it when you’re to change the gear ratios, so that’s something to look into. I might end up adding a DC motor drive to the leadscrew and calibrating it for different feed rates based on the required threading pitch or finish, but we’ll see in the future!
Steadies require work as well, one of them had two of the fingers shoved in place with a hammer (you could not move them at all by hand let alone by the tiny adjusting screws) so I had to deal with it and I’ll probably write a separate article on them, as I plan to spring load the fingers and I will toy with the idea of adding bearings to the fingers (possibly new fingers). So far I failed to acquire the correct spring wire thickness, since it wasn’t available at the music store, but we’ll get there!

 

Conclusions for now…

After you’ve dealt with all the issues and added your own personal touch, it becomes a very capable small lathe. However, as it comes from the box, it’s not really a usable piece of equipment. So be prepared to invest some money and lots of time into rebuilding it.
Don’t be discouraged though. Some of us cannot acquire big old lathes not for free not for a mountain of cash, so this is all we can get. Some of us don’t even have the space for a big old lathe, so there’s nothing to think about right there. If you plan to invest on one of these chinese lathes, simply assume it’s a kit. Everyone I’ve spoken to agrees with this notion, but we were all fine with it due to the aforementioned reasons. You do get what you pay for, but it’s not complete trash if you understand what’s involved in it’s proper setup.

Even though I had removed everything but the headstock and the spindle pulley, the bed itself with the headstock and gearbox still weighs around 80KG easily, at first glace you don’t really appreciate how heavy cast iron parts can be, even when hollow. I’m still thinking “what did I get myself into!?” but the end result should be very rewarding, so I must keep on going!

Most of what has been said applies also to the full gearbox models sold throughout the world, as most of the parts are the same.

That’s all for now, hopefully it’ll be of use to someone. I know I’ll be reading this when and if I have to take it apart in a few months or years!

Happy turning!

 

Taking apart the CQ6123B Lathe – Part 1

Posted by on July 12, 2013

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A few weeks ago I finally acquired my first metal lathe. It’s an import (Model: CQ6123B-750) from all the small Chinese bench lathes, this is probably one of the best, aside from the newer series with the spindle gearbox.

Before buying this lathe though I had looked into the available mini-lathes, they seemed nice but they didn’t meet all of my requirements, for instance a Unimat looks like a toy compared to this lathe. Don’t get me wrong, a well tuned mini-lathe can be a very useful piece of equipment, I just required a bigger distance between centers and some extra throw.

That said, lots of work can be accomplished with these import lathes… As long as you take them apart, clean them up, lube, reassemble and finish them with a nice calibration. There’s even some repainting involved, But it’s well worth it!

 

Getting started

Well, you’d think since it’s a new lathe you’d just set it up and go at it, but no. It’s nothing like it. Forget about the inspection sheet they give you, it’s a massive lie.

To begin with, familiarize yourself with the exploded views on the manual, you’ll need them because you’ll have to take the entire thing apart and reassemble it; that’s right.

The only portion I left in place was the headstock, my reasoning was that it should be aligned from factory and I didn’t want to go through the trouble of re-aligning it (plus I don’t currently own some of the tools required to do it properly).

Another good reason to take it apart is to make it easier to move and also to put less stress on the bed while doing so. But primarily because as-is it’s not really usable, or better put… You won’t get the most out of it and you may get into premature wear on several parts due to reasons I shall now explain.

You see, some parts are not even lubricated. Most of the lathe is covered in what’s called “shipping oil” which is most likely used, filtered motor oil. Similarly to cheap chainsaw bar oil (but in that case they may add thickeners, not always but quite often they do)

Here’s the problem with the shipping oil, as it dries up it ceases to provide lubrication, instead it provides protection. Well, that’s the intended goal, but it’s a problem for us because if we don’t fully remove it and oil everything up, we risk extreme wear of parts in a very short period of time.

One of the biggest shockers for me was finding no grease on the belt tensioner ball bearings, none whatsoever! — There have been instances of people complaining about “whining noises coming from the drive box” and it turns out it was the tensioner seizing up.

Another massive lack of lubrication was spotted on the apron, most of the gears were bone dry.

The lubrication ports provided are too small for most grease guns, they’re actually meant for thin machine oil but on an open gear system (that is, with no sump) you want grease on those gears, not thin oil. Unless they’re exposed to swarf, in which case you may want to stick with the lighter oil.

As per the actual lube ports, they’re of very low quality in fact the one by the side of the saddle (meant to lubricate the bed ways) had come apart causing the ball bearing and the spring to come loose inside the saddle. Not good at all.
Now, let me pause to make it clear this is not a series of complaints and assorted whining, it’s a narration of what I’ve encountered and what I’ve done to solve it. We all know what we’re getting into when we buy Chinese equipment like this, some of us have no other option so it is what it is.

I also haven’t gone through honing or “mating” the saddle to the ways yet, this is mostly a guideline on what I’ve done to get the lathe on a running state, we’ll deal about precision and feel later.

To begin I ran a quick inspection to determine whether everything was functional and nothing of importance was missing from the main assembly of the lathe. While the handles had massive play and everything had backlash, the gears where noisy and the overall feel was crap, it was all there (except for a live center and two combined wrenches which I suspect were stolen by whoever inspected the box prior to shipping it to my place, at the store) — Oh well…

 

Removing the apron

There are two variations to this method, I will explain how I actually did it and then I will present an alternative solution (now that I know how everything is assembled).

To remove the apron first you have to take the saddle off, and beforehand you have to remove the crosslide, and before that you have to remove the compound with the toolpost. Indeed, quite some work goes into getting to the actual apron, but don’t worry it’s doable and you don’t have to risk damaging anything if you follow the instructions carefully and you do it with patience.

The apron is held to the saddle by three allen screws, one of which is not visible due to the carriage being on top of it.

It’s a good idea to move the entire carriage to the far left of the bed for reasons that will soon become apparent.

To begin, remove the compound by undoing the two small nuts to the sides then pushing it up and sliding it off (or just remove the nuts and pull it up, then remove the two square bolts and replace them on the compound so you don’t lose them).

Now it’s a good idea to move the crosslide away from you, once you hit the limit back it off a couple turns. Remove the two allen screws holding the handle mount, keep it steady with one hand while turning the handle with the other, you’ll notice the shaft slowly begins to draw toward you. Be very careful not to bend or damage the leadscrew. Once it’s off, use some cotton cloth or bubble wrap on a clean bench to place it away from harms way.

The crosslide is now free to slide off, push it out carefully until it’s all the way out, the gib and the leadscrew protector will fall, so be very careful to put them back together and keep them together. The gibs you’ll most likely have to re-adjust anyway, but don’t worry we’ll get to it later. So far there’s nothing to worry about!

Now we can actually see the elusive third allen screw keeping the apron and saddle in place. To remove the saddle you’ll have to remove the two slide blocks, one is at the far end and the other one at the front. The big one at the back is held by three allen screws, the one at the front is held by two. Don’t be fooled by the third allen in there, it’s for the carriage lock, the tiny plate underneath locks the carriage when you fasten this allen screw. Surely we will soon replace it with an actual handle and a better block, but that can wait so let’s not get into a tangent!.

Before you go ahead and remove the three allens keeping the saddle and apron together, place some wood planks underneath the apron so that it doesn’t move once we do remove the bolts, reason being we don’t want to stress the leadscrew. If we bend or damage it in any way, we’re in deep trouble.

As the apron is now supported, feel free to remove the 3 allen heads and lift the saddle up, if it won’t budge double check that you’ve removed both slide blocks and the rest of the screws.

Once the saddle is off, make sure you don’t place it on the ways of the bed, instead have some more bubble wrap ready and place it somewhere else to clear the way.

The apron is now free, alright I lied. It’s free from the saddle, but not from the leadscrew. To proceed we have to roll it all the way off the leadscrew, however this is only possible if you move the saddle toward the left, not toward the right as you’d initially assume, because the leadscrew has a keyway that only goes to a certain point, this limits the movement of the apron for safety reasons.

First, the second roll/shear pin has to be punched out of the leadscrew shaft near the gearbox (toward the left), don’t worry these pins were a pleasure to remove on my lathe (I’ve had my “instances” with roll pins) since I didn’t have the right size punch tool (and you don’t want to use a center punch here, because it would expand the pin and we just want to push it out) I ended up using the shaft of a broken Dremel sharpening disk since it sits right over the roll pin. I braced the leadscrew mount with a 2×4 and some other scrap wood, so I wouldn’t impart force onto it’s rolling surface. A small (100 gram) hammer was used to punch the pins out, make sure as you are about to finally punch them out, that you turn the shaft to a side for clearance, otherwise the pin nearest to the gearbox will hit the cast iron shoulder and you won’t be able to remove it until you push it back and turn the shaft.

It’s not required to remove both pins to extract the leadscrew, only the far right one has to be removed. I removed both because I didn’t know this until I finally removed the leadscrew and noticed it’s only held by one of the pins.

Remember, this is not a race — take your time, be patient and very careful. We don’t want to harm the leadscrew or the halfnut in any way! — If you get frustrated, take some time off to do something else and come back with a cool positive mind. You can do it!

 

Now we have to remove the leadscrew mount at the far end of the bed. It’s held by two allen screws. However, first you should undo the grub screw on the leadscrew nut (look at the end of the leadscrew by the side of the mount and you’ll see it, regular allen grub screw right there on the nut!)

Now we need to remove the lock nut (that’s what I call it, the end nut that keeps a bit of tension on the leadscrew) to do this I had to use a vise grip, lots of cotton cloth and a 10mm wrench on the nut. Oh by the way, to do this you must be slightly insane or have a big pair of bawls. Maybe I’m tired but I have not found another solution that didn’t require shoving something into the drive gear to prevent the leadscrew from moving (I don’t like the idea and by the way the cotton rag protected the leadscrew and left no marks)

The only other way would be to clamp by the shoulder where we removed the roll pins, but that would impart torque all throughout the leadscrew, which is something I didn’t like either. When it comes to torque, keep everything as short as possible!

Removal of leadscrew mount on the lathe

Removal of leadscrew mount on the lathe

 

The trick is to wrap enough protective layers on the far end of the screw (to the left of the mount) so that we can grab it but not damage it with the vise grip, said vise grip will be set to a “light” clamp, not too tight — just enough so the leadscrew won’t move under a bit of torque.

Now we can remove the nut and undo the vise-grip.

DO NOT try to vise-grip the end of the leadscrew thinking you’ll get away with it, there’s a thread and you will damage it, in turn you will then damage the nut while trying to remove it and it will all become one big mess.

At this point we can actually knock the mount off, in my case it wasn’t budging because the paint was keeping it in place (they paint after assembly and often assemble while some parts are still wet).

The solution?, wooden mallet. You could try a brass or rubber hammer, I really really like the wooden ones. Don’t pry it with anything, just light taps to either side (horizontally, length wise and mostly toward the right — don’t knock on it from the vertical axis) until it releases gracefully.

After the mount is off, you can now slide the apron and leadscrew off. While you do this, make sure the wood planks track underneath it so that we don’t load the leadscrew down and risk bending it, likewise with the halfnut and gear assembly. We’ll be moving the apron to the left. It would be ideal to ask for help at this point, someone should keep the apron steady while we carefully slide the leadscrew off to the right.

There’s no way to remove it to the left (ie. moving the carriage to the right), since the key notch won’t allow it.

If all went well you should now have the leadscrew apart from the apron and the apron apart from the lathe bed!

 

Second alternative to removing the leadscrew:

In theory you should be able to pull the pin out from the coupling, remove the grub screw and the nut, remove the leadscrew mount and proceed to “unscrew” the leadscrew out to the right while leaving the apron in place. Make sure the half-nut is not engaged. This method should work, but I haven’t tried it yet. If this works, it would mean you don’t have to take as many precautions because there’s no leadscrew to be damaged anymore.

Remember:

Don’t force it, if something won’t budge don’t go nuts with a hammer, don’t try to cut corners. This takes time, I had to take several pauses and study the diagrams more than once before I went to remove each specific portion. I even asked around to see if others had done the same in the past or had any suggestions on the matter. A quick google search revealed no such information.

 

Asking for help is not a sign of weakness. If you know yourself you’ll know your limits and you’ll accept them for what they are, knowing that someone else may have already experienced what you are about to experience allows you to take a pause and listen to what they have to say on the matter. You can take it or leave it, but if you don’t ask and you don’t have the knowledge or experience, you may end up damaging something or worse. So by pure intelligence on your side, ask around. Asking for help is actually a sign of strength and not weakness.

 

I’m sorry for the lack of pictures, I actually wasn’t planning on documenting this. Once I put the lathe back together I’ll take pictures and post them here (in reverse order, of course).

More on part two coming soon (removing the motor, gearbox, electrics and more)

Have fun. Cheers!

 

 

DIY Refurbishing your espresso machine

Posted by on May 16, 2013

Leaky head?, Low flow rate?, read on…

Most of mid to low end espresso machines share pretty much the same pump and block assembly with very few differences, there are in fact just a few major designs out there most of which are aluminum/brass based and manufactured in China, however that doesn’t neccesarily make them bad.

In all inexpensive units (and some expensive units sold as “professional” but they’re actually a product of marketing bullcrap) the group head has a spring valve that opens when enough pressure builds on the head, this happens when the pump is turned on and it’s there to prevent water leakage. Some better units will use solenoid valves instead, which also allow to set the flow rate in some cases.

The passive valves used on inexpensive units require a clean surface to sit on, much like an engine valve does. The reason espresso heads can leak is simply because of an uneven mating surface (dirty valve seat or dirty valve) it doesn’t have to be a faulty part so if your machine leaks, don’t assume you’ll need rare / expensive spare parts to fix it. If you’ve taken good care of your unit chances are it needs a slight clean up and polish.

Like I said, this gparticular uide is mostly for inexpensive machines, I don’t have experience with high-end units as I’ve never had the pleasure to work with them.

 

Alright, bring it on!

To proceed, remove the water reservoir, portafilter and any loose parts such as filters, trays, etc. Tip the unit over, I use bubblewrap on the countertop to prevent scratches. In my case I had to remove the bottom cover (plated steel) which was held in place with 4 security torx screws.

Identify the type of head/block assembly, mine has a 12MM nut which holds the diffuser and forms part of the valve assembly itself. Other heads may use a notched nut or similar assembly allowing for a flat-head screwdriver to be used. Go ahead and remove it.

diy_espresso_head_before

A view into the brew head before cleaning it, you can clearly see it’s become obstructred. The valve was in even worse shape!

The valve is often spring loaded and has a silicone seal / head. This is where some of the sediment build-up occurs and prevents it from sealing the boiler properly. But most of the build-up occurs on the valve body, which is often (but not always) brass, on more expensive units you may also find stainless steel parts.

Once you’ve removed the nut pull out the spring if it didn’t come out on it’s own, now that the entire valve assembly has been taken apart, use a flashlight to look into the valve body, you’ll probably find the opening to the boiler is slightly (or severely) restricted with build-up.

If there’s no way to remove the bottom of the unit, you’ll need to work with a mirror to look into the boiler.

diy_espresso_head_valve

Valve assembly after clean-up.

To proceed with the clean-up of the valve body you’ll want to use ~300 grit sandpaper (emery cloth) and then 600 to finish off. You could use your Dremel / rotary tool with a fine brush attachment used for polishing brass (don’t use any compounds, just water) but you have to be very careful not to damage the threads or the valve seat, if you increase the original diameter there’s a chance the valve could pop in and float inside the boiler, allowing all of the boiler contents to spew out and it would never seal again forcing you to replace the entire valve head which may end up costing quite a bit of money and may not even be worth it on inexpensive units. Another possibility is for the bulb to catch and get stuck, so beware of the Dremel and abrasive tools.

 

After cleaning and polishing, it looks brand new!

After cleaning and polishing, it looks brand new!

If you want to make sure all the surfaces are neatly cleaned up and polished, you can use an old lead pencil as a former to wrap a piece of sandpaper around, tapering the top into a cone and then inserting it inside the valve body (with water) you’d proceed by twisting it a few times, removing it, inserting some cloth or paper towel wrapped around to clean up the valve and then take a look inside with a flashlight, repeat until it’s all nice and polished, specially the valve seat.

The silicone valve in my case had a lot of build-up but was easily removed by hand, don’t use any abrasives on it and try not to scratch it in any way.

Now that you’ve cleaned it all up, go ahead and add some water with the unit standing on it’s usual position and give it a few flushes, any loose pieces of build-up should come out, as well as anything you’ve unwillingly introduced while cleaning and polishing the valve body.

 

This is how the assembly goes, valve bulb/head pointing up.

This is how the assembly goes, valve bulb/head pointing up.

If all looks good, go ahead and assemble the valve back to it’s original state. The silicone valve goes facing up into the valve seat, make sure the spring is nice and clean as well as the silicone valve head. If you see any damage on the silicone it’s time to replace the valve or come up with a makeshift solution…

Once it’s all assembled, torque the nut down making sure your diffuser disc / plate is in the right position and turn the unit on, give it a nice flush.

 

In my case the diffuser was slightly blocked so I had to clean it up with a needle and lots of patience before I installed it, This procedure made heaps of difference. Basically my espresso was not only leaky but also had low flow rate and it sputtered a lot making it difficult to obtain a straight shot with good crema.

 

Next in my list would be to access the pump to see if there’s a pressure relief adjustment and go ahead to calibrate it up to 9BAR at the head, that however is going to be a whole ‘notha quest for me. In that event I may probably end up refurbishing the pump as well.

 

Hopefully this guide has been of use to you!
And as you know, don’t send your machine to the store… A good barista fixes his/her own espresso!

 

Have a good one,
Gus

UT61E Protocol Description

Posted by on March 18, 2013

Intro:

The protocol used by the UT61e is quite simple, each packet contains 14 bytes. It constantly streams packets as the screen is updated at around 2 packets a second. The 14 bytes are basically a string where the range, digits, function, status are contained.

The serial interface settings are:

19200 baud, odd parity, 7 data bits, 1 stop bit, no handshake.

Describing the protocol:

This snippet shows you how the data is separated, I handle the 14 bytes as a string, which simplifies the process of separating each portion and since this is a low sampling rate application with low priority, it’s not a resource hog.

If ReadSerialPortData( port, @inp, 14 )
 
	If AddElement( *this\sample() )
		*this\sample()\range 		= Asc(Mid(inp,  1))  ; RANGE
		*this\sample()\digits		= Mid( inp, 2,  5 )  ; DIGITS
		*this\sample()\function 	= Asc(Mid(inp,  7 )) ; FUNCTION
		*this\sample()\status		= Asc(Mid(inp,  8 )) ; STATUS
 
		*this\sample()\option[0]	= Asc(Mid(inp,  9 )) ; OPTION 1
		*this\sample()\option[1]	= Asc(Mid(inp, 10 )) ; OPTION 2
		*this\sample()\option[2]	= Asc(Mid(inp, 11 )) ; OPTION 2
	EndIf
 
EndIf

I believe the last two digits are the “end of packet” limiter (CRLF) however I currently cannot test this, I wrote the code a long time ago and I forgot to comment on this slight detail, but as you can see I’ve defined the CRLF contants, so it must be there.

A list of constants:

Here are some constants from my UT61e (unpublished) library…

#FUNCTION_VOLTAGE 		= %0111011
#FUNCTION_AUTO_CURRENT_UA 	= %0111101
#FUNCTION_AUTO_CURRENT_MA 	= %0111111
#FUNCTION_CURRENT_22A		= %0110000
#FUNCTION_CURRENT_MANUAL_A	= %0111001
#FUNCTION_OHMS			= %0110011 
#FUNCTION_CONTINUITY		= %0110101
#FUNCTION_DIODE			= %0110001 
#FUNCTION_FREQUENCY		= %0110010
#FUNCTION_CAPACITANCE		= %0110110
#FUNCTION_TEMPERATURE		= %0110100
#FUNCTION_ADP			= %0111110
 
#RANGE_ONE			= %0110000 ; Example: 22.000nF
#RANGE_TWO			= %0110001 ; Example: 220.00nF
#RANGE_THREE			= %0110010 ; Example: 2.2000µF
#RANGE_FOUR			= %0110011 ; Example: 22.000µF
#RANGE_FIVE			= %0110100 ; Example: 220.00µF
#RANGE_SIX			= %0110101 ; Example: 2.2000mF
#RANGE_SEVEN			= %0110110 ; Example: 22.000mF	
#RANGE_EIGHT			= %0110111 ; Example: 220.00mF
 
#DIGIT_0			= %0110000
#DIGIT_1			= %0110001
#DIGIT_2			= %0110010
#DIGIT_3			= %0110011
#DIGIT_4			= %0110100
#DIGIT_5			= %0110101
#DIGIT_6			= %0110110 
#DIGIT_7			= %0110111 
#DIGIT_8			= %0111000
#DIGIT_9			= %0111001
 
#STATUS_OL			= 1 < < 0
#STATUS_BATT			= 1 << 1
#STATUS_SIGN			= 1 << 2
#STATUS_JUDGE			= 1 << 3
 
#OPTION1_RMR			= 1 << 0
#OPTION1_REL			= 1 << 1
#OPTION1_MIN			= 1 << 2
#OPTION1_MAX			= 1 << 3
 
#OPTION2_0			= 1 << 0
#OPTION2_PMIN			= 1 << 1
#OPTION2_PMAX			= 1 << 2
#OPTION2_UL			= 1 << 3
 
#OPTION3_VAHZ			= 1 << 0
#OPTION3_AUTO			= 1 << 1
#OPTION3_AC			= 1 << 2
#OPTION3_DC			= 1 << 3
 
#UT_CR				= %0001101
#UT_LF				= %0001010

That’s all for now, I currently don’t have a serial interface to test with (Ain’t got the USB cable either) so I can’t finish the library as to post it, but hopefully I’ll get it done eventually.

The supplied software by UNI-T is pretty bad and it’s Windows only, hence the drive to write my own.

As it is, it should give someone a head-start if they’re about to write their own front-end. On the datasheet of the UT61e controller it’s all explained in fine detail, but I can’t recall the number at the moment.

This whole thing was part of a bigger picture, but I had to give up the concept due to lack of funding.

Alright, enough of this shoulda, coulda, woulda!

Cheers,
Gus