Anybody familiar with Drukov grinder? - Page 2
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  1. #21
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    EKretz: I just found this post, as I was searching for information about this same unit I have. Mine is single phase motor.
    I have the manual I got with it. I purchased it new ~1994 or so from Enco. It came in a big wood box intended for storage.
    You said you found the manual for it via google, all I'm seeing is non English. The manual I have is 10 pages, and English, but no diagrams.
    20210105_201143.jpg20210105_200957.jpg20210105_201045.jpg20210105_201100.jpg20210105_201117.jpg

  2. #22
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    [QUOTE=ignator;3687961]Next pages
    /QUOTE]
    20210105_201020.jpg
    20210105_201135.jpg

    Hope these photos are readable once seen on the computer screen.
    I've only used mine a few times in the years I've owned it. I'm currently working on rebuilding a spindle for a not to be mentioned surface grinder. The valued engineered every ounce of operational use from it. We shall see if replacing the ABEC0 bearings with ABEC7 does anything to surface quality.
    Attached Thumbnails Attached Thumbnails 20210105_201117.jpg  

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    Cool, thanks! The only other version I found was that one in Czech, so I was only able to glean what I got from translation of that text via Google. I'll look over the English version and see if there's anything else useful, thanks for taking the time to add the photos. Mine came with the big wood box too.

    How do you like the toolpost grinder?

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    Quote Originally Posted by eKretz View Post
    How do you like the toolpost grinder?

    It has worked well the few times I used it. One earlier fix was for my lathe, that had an incorrect quill tailstock from the factory. #4MT tooling would not seat, as they had a machining error that prevented the tang from seating. The replacement part was about 0.0015" too large, so I used the grinder to reduce it's diameter. I got good surface finish.
    The previous use was with that long extension spindle for internal grinding on a cylinder.
    Mine came with 3 hubs, 2 of them fit 1-1/4" wheels, the 3rd is for a 2" wheel.
    I just swapped out that long spindle to the short one for external grinding. I've never used those small internal grinding arbors. But I'm going to see if I can fix some surface grinder hubs, that seem to run eccentric.

    The confusion I have about the spindle with the eccentric feed, it seems that would not be linear over it's range. Seems there should be a cosine error. Probably does not matter as measure twice always applies.

    If this TP grinder works well with the spindles I have for small internal work, I will be looking for spare grinding wheels for those, I've not looked to see what metric size I assume they are. The diagram shows just the external dimensions.

    I think I paid $600 or $800 back when I purchased this. Enco had it on sale in their monthly catalog. My memory was that the US name brand was 4x the price, and didn't include all the accessories.

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    I find it interesting that two of you have grinders with single phase motors, as the manual has listed the grinder being equipped with a three phase motor, as mine has. They must have sold it differently depending on where it came from. I'm pretty sure mine came over with it's Euro owner, as the original owner described to me by the guy I got it from was perhaps Czech or German. I think that the slight amount of cosine error isn't realcritical in the range of movement that the spindle is capable of - that's probably why it only has graduations for a certain range. I think probably it would be a good idea not to use the eccentric fine adjustment when grinding a taper though. I got lucky in that my grinder came with quite a stack of spare grinding wheels, including the tiny ones for the micro arbors.

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    [QUOTE=eKretz;3688180three phase motor[/QUOTE]
    I wish mine was three phase.

    I have some fixing to the tool post mount to put the grinding wheel at center height. I reused the adapter I made from the smaller lathe, and at the time it was not critical to be on center. But with a taper it is.
    We shall see if I can hold tens in fixing the current problem of wheel hop. As built the original wheel hub wobbles on the spindle taper. I'm assuming it's the hub, but making a precision test spindle, and mounting that on a surface plate with the precision bench center is probably the only way to determine what is screwed up. And that's machining I've never done before. It always seems the amount of alligators in the swamp goes up. I will learn something......

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    Quote Originally Posted by optoeng View Post
    I just put my Drukov up on ebay, since I no longer have a use for it. Thanks for posting the Manual pdf.
    and I'm now the proud owner of it. Received Friday, unpacked it and played around with it Saturday. Made a sleeve that goes over the toolpost bolt that allows me to secure the grinder to the compound.


    img_5276.jpg
    Here it is mounted.

    img_5277.jpg
    About 2" tall, 1.5" diameter at the top, 1.120" or so on the bottom.

    img_5278.jpg
    Added a washer. (I only had 1.5" diameter stock, or I would have used something bigger).

    img_5280.jpg
    Decided to try and blue it with my HotShot 1200 heat treat oven. A little too blue, I think I was a but too hot.

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  10. #28
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    I was not having problems with the grinder when it was set up with the long internal spindle (about 10 years ago was last used). But I'm now seeing surface finish issues on a 1 inch diameter bar, with a 3"/foot taper for an arbor external grind with 5 inch wheels. It looks faceted. I've tried 3 different wheel types, with 2 different hubs. Also from bottom lathe spindle speed of 48 RPM up to 200 RPM just to see if it had any affect. No change to finish. Seems there is vibration from the motor, and I can feel the whole grinder shaking with this low level vibration.
    So after fighting getting the pulley off the motor, as the removal tool bottomed out before contacting the shaft. I find the shaft has about 1.5 thou runout. Is this normal for a tool post motor? It just seems to cause vibration.
    EKretz, as your motor is 3 phase you may be seeing a different behaving machine then mine.
    So I'm about to try to remove the tapered sheave on the motor shaft, and see what the bearings look like, and if the motor rotor was ever balanced.
    I wish I had some way to check the balance. But I don't think I should be seeing 1.5 thou runout on the shaft right next to the motor bell housing.

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    I am going to run mine for the first time tomorrow morning regrinding some chuck jaws, I will check the runout of the spindle before I start. I will be somewhat disappointed if it's much over a few tenths. I suspect you have something bent or possibly someone replaced the bearings with lower quality ones or something along those lines.

    I do think your lathe rpm is a little low, that might be some part of the "faceting" you're seeing. At 1" diameter I would try setting the lathe for between 300-400 RPM. Start at the low end and work your way up. Generally I find good results around 80-100 feet per minute on the grinding surface, rotating opposite direction to the grinding wheel. And I would say maybe you should make a wheel balancer, but if your spindle is way out of balance it probably won't help you much.

    On re-reading, do you mean the motor shaft is running out? The spindle is good? I think I may have mis-read that the first time. If that's the case, maybe you should try changing the motor bearings and while the shaft is out check it for straightness with an indicator in some v-blocks.

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    I had bought this new from Enco ~25-30 years ago. So the bearings and motor have never been touched. Things may have gotten damaged in the shipping from Europe to here, to me. I hope I'm not dealing with a bent motor shaft.
    I had messed with the setup the previous day. I made a new T-nut (T-plate) for the compound T-slot, as the one from the previous lathe I used this grinder on was marginal in this larger T-slot. And I only drilled and tapped one hole 1/2-13 for mounting the sub-base that is a riser for the tool post grinder, to get the wheel center on height to the lathe spindle center. That sub base was machined to remove ~1/4" of material to its thickness to put the wheel on center. So I added another drill hole in the sub base, and tapped a hole for it in the Tnut.
    The mounting hole (that huge slot) of the grinder then has a large 1/2" steel plate acting as a washer, and 1/2" hex head cap bolt to hold the grinder onto the tool post via the riser block (which is tapped for the 1/2-13 threads). That is still not rigid enough, as I was leaning over from the right side to see how much sparking out was occurring, and I pushed the wheel into the work. I really don't know where all this compliance is, but I'm thinking it may be normal in this ten thousands world where everything is plastic enough.
    I need to make a mandrel so I can balance wheels, as earlier this summer I bought a wheel balancer, the type with the large disks.
    I will split the motor and see if the rotor had ever been balanced. But there appears to be vibration from that after removing the pulley drive sheave. That's when I measure that taper sheave having runout. So I put the indicator right on the motor shaft and saw the same.
    I can see a swash plate of the grinding wheel, so that too has out of balance issues. I built a wheel dressing tool that clamps to the ways of the lathe, but that is so cantilevered that I know it's not rigid enough to true the sides of the wheels.
    Reading posts on this site, there are those that say you must balance wheels, and those that say for these small of wheels, you don't need to balance. Feeling the shaking of this grinder, something(s) out of balance.

  13. #31
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    Quote Originally Posted by ignator View Post
    I had bought this new from Enco ~25-30 years ago. So the bearings and motor have never been touched. Things may have gotten damaged in the shipping from Europe to here, to me. I hope I'm not dealing with a bent motor shaft.
    I had messed with the setup the previous day. I made a new T-nut (T-plate) for the compound T-slot, as the one from the previous lathe I used this grinder on was marginal in this larger T-slot. And I only drilled and tapped one hole 1/2-13 for mounting the sub-base that is a riser for the tool post grinder, to get the wheel center on height to the lathe spindle center. That sub base was machined to remove ~1/4" of material to its thickness to put the wheel on center. So I added another drill hole in the sub base, and tapped a hole for it in the Tnut.
    The mounting hole (that huge slot) of the grinder then has a large 1/2" steel plate acting as a washer, and 1/2" hex head cap bolt to hold the grinder onto the tool post via the riser block (which is tapped for the 1/2-13 threads). That is still not rigid enough, as I was leaning over from the right side to see how much sparking out was occurring, and I pushed the wheel into the work. I really don't know where all this compliance is, but I'm thinking it may be normal in this ten thousands world where everything is plastic enough.
    I need to make a mandrel so I can balance wheels, as earlier this summer I bought a wheel balancer, the type with the large disks.
    I will split the motor and see if the rotor had ever been balanced. But there appears to be vibration from that after removing the pulley drive sheave. That's when I measure that taper sheave having runout. So I put the indicator right on the motor shaft and saw the same.
    I can see a swash plate of the grinding wheel, so that too has out of balance issues. I built a wheel dressing tool that clamps to the ways of the lathe, but that is so cantilevered that I know it's not rigid enough to true the sides of the wheels.
    Reading posts on this site, there are those that say you must balance wheels, and those that say for these small of wheels, you don't need to balance. Feeling the shaking of this grinder, something(s) out of balance.
    If you have a thou and a half of runout on the motor shaft, that might be enough to set up a pretty good vibration all on its own. The weight of the pulley and motor shaft itself would be enough to create a pretty good vibration if it's running out. Balancing the wheel is more important on something like a lathe toolpost grinder than on a surface grinder IMO - due to the added compliance in the stack-up of loose fits in a lathe as compared to something like a surface grinder which is generally a lot stiffer in comparison.

    For dressing I would be looking to set up a dresser either clamped to the workpiece or clamped to the chuck. Having something hanging off the ways would be too floppy unless it's extremely bulky IMO.

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    Okay so just for reference, my motor pulley runs out about a ½ thou. The O.D. spindle itself is within tenths, but the wheel adapter runs out almost .002" - looks like a not very good fit on the taper. We'll see how it works.

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    I did a repair on one of the aluminum pulleys that is attached to the motor shaft steel taper. It had part of the casting broken out. This was the pulley that the jack screw removal tool bottomed out in, as I think the taper was machined slightly less then require, so the jack screw bottomed out before the end contacted the motor shaft to push the pulley off. They didn't break any edges from what I can see of the machining at least on the aluminum parts of this. I think that's why this had broken out. It might say it's not very quality aluminum. These probably were made when still in the USSR.
    I'm working on making a much sturdier mount to the T-slot. The riser was made of aluminum, which had two half inch hex head cap screws holding it to the compound, then the grinder sat on that with a single 1/2" bolt holding down into a threaded hole in the riser. I'm making a new riser out of steel, and will have two cap screws when finished, but they will go all the way down to the T-slot nut. I didn't have any steel plate of that thickness in my source pile, so I'm starting with a 6" steel 1018 drop, that I band sawed off a piece 1-1/4" thick, and just started machining that to the 1.175 thickness of the previous riser. Then I need to slice an edge off so it fits between the spindle and the motor area with maximum contact to the lathe compound top.

    Now I need to check the pulleys for runout as well. I just know that I need to make this whole assembly more rigid to the lathe.

    I live for projects where you fix the tool, to fix the tool, to fix the tool. This all started out as a task to repair my cheap surface grinder, now the tool post grinder is in series. It needs to happen as I have another project needing this tool.

  16. #34
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    Oh yeah I hear you on the fixing the tool to fix the tool. That's often an everyday thing for me too. I just made a spacer to mount the grinder today also. I went with 4½" diameter stock turned down to 1⅛" where it goes through the grinder, that snout just long enough to be slightly shy of the top surface of the grinder. 49/64" drilled hole through the middle for the hold down bolt. It's pretty rigid seeming so far. I've just now got the grinder wired up with the VFD. It's running smoothly, very little vibration.

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    Well, grinding the jaws went without a hitch. No vibration issues.

    https://youtu.be/SUlEbQhBYH4

    And I didn't have anything to cover the ways or I would have... Not my shop, nothing was available.

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    I know the motor on mine is out of balance. It's another thing to take apart and see if I can correct it. I haven't gotten to the wheel balancing arbor yet.

    I think that's why I didn't notice this issue, as I was using that long spindle for internal grinding ~10 years ago. That small wheel didn't get the same drive from the motor balance. And it's small size helped in balance as well.

    But now I need precision, to correct the spindle on the surface grinder. It was what I could afford back 25 years ago. Tearing into it, it does not have angular contact bearings, but just non precision deep groove. So it suffers wheel hop surface finish, at least that's what I would call it. It does work, but just leaves the surface finish horrible, I guess I could pass it off as micro hand scrapping finish. It too is single phase motor which is one motor shaft spindle in one. It looks like it was intended to have angular contact bearings, I don't know why they didn't put them in. I found a pair, but that's part of the project as the bearings have no shields or seals, so I machined the flange boss next to where the double row bearings are, and put a seal in that. That will seal the motor side from the bearings. It is a TEFC motor, that needs a new fan as it was plastic, and distorted, and added vibration. I need to figure out how to seal the wheel side. They do have preload nuts on the shaft. So I'm thinking they value engineered this to hobbyists. It looks exactly like the one that Grizzly sells. At the time, craigslist/ebay and other sources did not exist. Which would be my path if I were to get one today. So I will fix junk. It's what I do.

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    Yikes, just plain ball roller bearings? Now I'm going to have to tear into mine and see if that's the case with it also. I would have expected angular contact as well. Mine did produce a pretty decent surface finish on the jaws though.

    20210118_183057.jpg

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    I was wondering when watching the video how you got past that preload ring. But I see from the photo the jaw has a step on the front edge.
    How much runout did the chuck have?

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    About .010" - but I don't expect that will get fixed by grinding the jaws. And yeah someone cut a counterbore into the jaws. Not really my thing but it helped with a quick and easy preload. Will have to grind the step also. The chuck is pretty beat and has pretty bad scroll wear. Not sure the owner of the chuck wants to chase that down and actually repair it rather than just replace it. The main problem was jaw wear/taper - so the work wasn't being held solidly. Trying to take any kind of cut without a center resulted in the part wobbling every which way. Gotta grind the front faces of the jaws too. You can see the wear pretty clearly contrasted with the fresh ground surface in this shot.

    20210118_172455.jpg

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    Even the lathe ways look beat. Hope this fixes the 'bell mouth' wear of the chuck.

    I'm finding problems I never thought I had with my lathe bought new in 2004. It was affordable, and brand new. But I've become convinced it was made from every scrap part. It never showed up in the catalog as a model G3621 (16x40, I'm guessing they imported about 6 of them, per their tech support). But I wanted a big bore machine for shaft work. I just found that facing the 6 inch disk, has a concave face of about 1 thou per inch, when I checked it on the surface plate. I just never did that check before. I only noticed it, as I put it on a belt sander, and noticed the edges sanding first. It turns damn straight though, and that's the major use. I replaced the chucks that came with it with Bison 12 inch 6 jaw zero set, and a Pratt Burnerd 4 jaw. And that makes all the difference in turning with minimal runout. I had the tailstock off last night as it seems to have alignment issues (drilling a center on the mandrel). Scraping and line boring is beyond what I want to do to fix both these issues.

    I'll continue work on the T-slot mount, and a mandrel for balancing the wheel. I just hope I can get rid of the faceted surface finish. The test grinds I did on Sunday, the hub looks good with blue Hi-spot, but just does not have a self holding fit. It's a 3 in per foot taper on the surface grinder. I don't want to make that spindle worse, but I find the taper has runout relative to the ball bearing machined lands, about 2-3 tenths.


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