Tramming and quill lock Warco WM18 / Grizzly G0704

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charkmandler
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Tramming and quill lock Warco WM18 / Grizzly G0704

Post by charkmandler » Mon Jan 10, 2022 7:32 pm

HI, I have a Warco WM18 mill, similar to the Grizzly 0704. When tramming up the head / spindle I find the quill lock tilts the spindle out of tram by about .001". The quill lock is just basically a bolt with a brass end that presses against the side of the quill. In the past I'm sure I saw a modification for a quill lock that overcomes this but all I can find is spindle locks, which are a different thing.

Tramming the head without using the quill lock but with different quill extensions using the fine feed results in consistent readings. I could tram the head with the quill locked but this gives different and inconsistent readings depending on how tight the lock is tightened.

For those that are not familiar with this mill it is a hobby type mill and does not have a knee.

Any suggestions please?

Harold_V
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Re: Tramming and quill lock Warco WM18 / Grizzly G0704

Post by Harold_V » Mon Jan 10, 2022 7:41 pm

If tightening the lock tilts the spindle, I'm not sure any other type of lock would help. The real problem is excessive clearance between the quill and housing. If you can't eliminate that, the quill will deflect under load, locked or not.

H
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Bill Shields
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Re: Tramming and quill lock Warco WM18 / Grizzly G0704

Post by Bill Shields » Mon Jan 10, 2022 8:59 pm

Split the difference and call it a day.

If the locking bolt moves the quill that much you can be sure it will move that amount when cutting
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charkmandler
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Re: Tramming and quill lock Warco WM18 / Grizzly G0704

Post by charkmandler » Tue Jan 11, 2022 4:26 am

Thanks Harold, yes what I feared. Unfortunately I don't have the money for a precision mill. It does a pretty good job on repeat items but there are compromises.
Bill, split the difference, I think that could be the compromise I'll have to make.
Thanks

pete
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Re: Tramming and quill lock Warco WM18 / Grizzly G0704

Post by pete » Tue Jan 11, 2022 2:11 pm

If it's a Warco machine then your likely in the UK. If I remember correctly I've seen a split quill clamp for that mill design fastened to the bottom of the head casting on either a forum post or Youtube video at some point. I haven't searched, but given that quite a few cnc the Grizzly G0704 and if that modification can be found anywhere it's probably mentioned a few times here. https://www.cnczone.com/forums/ Or possibly with a Youtube search with maybe GO704 modifications as the search term might bring a video about it up. The exact details are a bit hazy, but I think it was pretty much a round stepped aluminum ring starting with maybe 1/2"-3/4" thick plate with three or four allen head cap screws through the step and into the head. No mounting bolts over the last 25% or so of the ring that has to move during clamping. And I think it was mentioned the ring was always lightly clamped during any quill movement to prevent that spindle tilt. Boring for the quill diameter would be fairly critical to get it close enough. That split ring would also lose you a bit of total quill travel because of how it has to surround the quill to clamp it, so keeping it's depth to the bare minimum would also be important. Steel would be better than aluminum both for it's strength and coefficient of friction, but the additional wear on the quill would make it a much poorer choice I think.

It wouldn't be ideal for some milling tasks, but tramming the head with the spindle lock engaged and the spindle fully retracted while using only the head Z axis on the column with it's hand wheel for your Z axis moves would probably be the most rigid and repeatable method to keep the head alignment correct. That loses your built in quill dro of course, but a dial indicator against the bottom of the head would allow fairly accurate moves in Z. Another and I think much better design for quill locks than you currently have is known as a split cotter. It's used on many machine tools, Bridgeport type mills, lathe tail stocks etc. Even if you could re-machine to add one, and I've no idea if there's room on the head to do so. That still doesn't remove the clearance that's allowing your quill to move within the head. I'd guess that's why the addition of the bottom mounted quill clamp was used instead. You didn't mention it's been done, but to go to the effort of adding that type of quill clamp, your mills initial column and head alignment has to be almost perfect in X,Y to justify trying to correct the problem with the quill tilting. And that's a fairly involved task.

charkmandler
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Re: Tramming and quill lock Warco WM18 / Grizzly G0704

Post by charkmandler » Wed Jan 12, 2022 8:16 am

Thanks for your input Pete, I'm sure I saw something but spent some more time searching last night with not luck. There are several designs for quill stops but not locks. Although there is .001" of movement when using the lock I have not had any problems with vibration or chatter, so I think a design along the lines that you mention should be the best that I can do at this stage. There is no meat in the casting to fit a split collet.

For the job in hand I've got the mill trammed up pretty much spot on. I did discover an odd effect of using the tram lock that can fine adjust the tramming - while tightening the head (I've added the two extra nuts as recommended) the tram lock stops the head rotating to the right, clockwise, but after a test cut and recheck the tramming the head has rotated clockwise so tramming is out .001". This I think is tension caused by tightening the head working its way out when making interrupted cuts with a fly cutter. The solution is to tram the head to the left by .001" and then tighten the head - after a test cut it works out the tension and corrects the tram. I did fit a adjuster on the other side of the head but the problem is caused when tightening the nuts.
I spent some time getting the column correct to the base with the purchase of a 15" square. Y axis is out by about .005" over 8" so I really cant complain for a hobby mill. Still miss the big mill I used to have.

Mr Ron
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Re: Tramming and quill lock Warco WM18 / Grizzly G0704

Post by Mr Ron » Wed Jan 12, 2022 2:54 pm

Unfortunately, there is not much you can do to correct the problem other than to replace the quill with one that fits the housing closer than the original one. A ring around the quill could work if there is enough room to attach it to the housing; but this would require much work to accomplish. The ring could be made of brass but attaching it to the housing would require turning the housing 180° and precision locating/drilling and tapping for attachment screws/dowel pins. Possibly the ring could be attached to the housing using epoxy, letting it set before drilling and tapping. .001" really isn't too much for a hobby type mill. I would just live with it.
Mr.Ron from South Mississippi

pete
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Re: Tramming and quill lock Warco WM18 / Grizzly G0704

Post by pete » Wed Jan 12, 2022 5:21 pm

That would be tough to go from a much bigger mill to something smaller and less user friendly. I moved up from a Seig X2 sized mill to a 3/4 sized Bridgeport clone. Much easier to use in every way. That split collar design I've seen somewhere in the past may or may not have been for your exact mill so I can't say for sure if it will even work for you. It would also be a fair amount of work to pull and strip the head down to it's basic casting. It's even likely to require machining a true flat area just outside your spindle bore on the bottom of the head casting for that collar to seat against and have it's bore stay square to the spindles vertical axis. I guess only you can judge if it's possible or even worthwhile on your machine. If it will work, then using it and the factory quill lock at the same time would give you at least two points the quill is held in position so much more rigid and stable as well. But as others have said, .001" really isn't that much except when using larger diameter cutting tools. You might see more beneficial gains getting your column and spindle aligned a lot closer to being true to the table. Most conventional squares are fairly tough to verify there true over long distances, even some quite expensive one's have allowable tolerances that make there accuracy for that column and spindle checking doubtful. For that reason I much prefer either making or buying a cylindrical square for alignment checks like this along with a dial indicator against the square for your Z axis checks. That type of square is easy to check with just micrometer measurements along there length, and even if there's small deviations, there then known and can be compensated for. It does take a pretty good condition lathe that is aligned to turn parallel to fairly close limits to make one though.

Since I don't know what you do or don't yet know and you mentioned fly cutting and knocking your head out of tram. There's many Youtube videos and even forum postings showing or mentioning substantial depths of cut with fly cutters. The tool itself is capable of it, some are even meant to do so. The Tormach super fly and Surburban Tools fly cutter as two examples. But our mills were never designed for that. When there brought up, all of my older machining references mention there a light finishing tool only. With my much larger mill I'll limit my depths of cut to maybe .010"- at the very most .015" in aluminum and roughly half that in steel or stainless. If you know what it sounds like, you can literally hear the spindle splines hammering back and forth in some of those YT videos. It's doing exactly the same to your spindle bearings. A multi tooth face mill works differently, once the tool is far enough into the cut there should be two or more cutting tips doing the work through the tools full rotation so the cutting loads are constant and the spindle splines and bearings are fully loaded in just one direction.

charkmandler
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Re: Tramming and quill lock Warco WM18 / Grizzly G0704

Post by charkmandler » Sat Jan 15, 2022 7:56 am

Yes Pete a cylindrical square would be best but not to hand, the tramming is pretty spot on whether at the top of the column travel or bottom. I made up a 6" steel disc on a R8 arbor for the fly cutter and its very smooth but as you say the extra diameter magnifies any error. When testing I only took a cut of about '002"; it's defiantly the 'spring' in the head when tightened with the stops engaged, I've found that I set the stop to stop the head .003" out of tram anti clockwise (looking at it) and then release the stop and tighten. Tightening twists the head about .003" - takes a few goes to get spot on. I've now done several jobs that needed flycutting and the tramming has not moved .
I've just flycut the top of some Vincent crankcases (mentioned in a previous post ages ago) and am happy that any error between the bearing axis parallelism with the crankcase is less than .00025". This was a job far to big for the mill but a solid setup worked well. The attached photo shows the setup before final clamping - the angle plates are adjustable and I had dial gauges on the mandrel through the main bearings while tightening to make sure nothing moved.
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87DF5141-2323-4510-9824-6A7D3C2D1BA1.jpeg

pete
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Re: Tramming and quill lock Warco WM18 / Grizzly G0704

Post by pete » Sat Jan 15, 2022 6:06 pm

That's a complex and time consuming set up to do, well done.

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