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I'm fairly new with the DB 200, and I'm trying to figure out how you mill with it. I can see the X-Y movement with the milling table attached to the cross-slide, but how do you accurately control the vertical cut depth ? I don't see any kind of a fine depth of cut adjustment, or do you re-adjust the milling head on the vertical shaft every depth change ?
Cheers
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Kevin Groenke @ PersonMakeObject
Z-axis in milling set-up is a significant problem. When I do it I use the quill feed on the headstock but accuracy is not inherent. There are some Unis with an aftermarket z-axis feed mechanism out there, but they're pretty rare. Search the group for "UPVLA" for previous discussion of it.? Kevin from PersonMakeObject
I'm fairly new with the DB 200, and I'm trying to figure out how you mill with it. I can see the X-Y movement with the milling table attached to the cross-slide, but how do you accurately control the vertical cut depth ? I don't see any kind of a fine depth of cut adjustment, or do you re-adjust the milling head on the vertical shaft every depth change ?
Cheers
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Hello
Slynch:
This is
one weak feature of the Unimat. There is no graduations for
vertical movement. You can move the quill and not loose
location, which you would loose if you moved the milling head.
You could use an indicator to watch how much the quill moves.
Take
small cuts, it isn't a heavy duty machine.
Carl.
On 7/9/2022 9:03 PM, slynch wrote:
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I'm fairly new with the DB 200, and I'm trying to figure out how
you mill with it. I can see the X-Y movement with the milling
table attached to the cross-slide, but how do you accurately
control the vertical cut depth ? I don't see any kind of a fine
depth of cut adjustment, or do you re-adjust the milling head on
the vertical shaft every depth change ?
Cheers
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You can make a scale to go around the feed lever that will give a fair indication of depth, but that doesn't help with repeatable accuracy. You can get digital scales for reading tread depth on tyres that cost very little and could be fitted up for an accurate reading. To control the depth without adding complicated fine feed mechanisms you could add a stop screw, ideally with a nice fine thread, and bring the head down onto it when making a cut. This will be fairly rigid, On the next cut adjust the screw a little and bring the head down to the stop again. A friend used this technique on quite large mills and found it worked well. He would set the stop correct for the final depth and add shims, removing them one by one to control the depth of each cut. It was quicker than fiddling about with dials and readouts, and his main concern was accuracy with speed, since he was on piece work.
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A timely thread for me. I acquired a used milling table for my SL earlier this year. So far I've only used it for drilling but in the past week have been making some extra 'T' nuts so I thought it would be nice to mill the flats on the SL.
For this job I gave up trying to use any 'Z' feed - I just set the 'Z' to the right place once and then locked the quill with the two clamping screws. I then used the side of the cutter, probably stepping over (on the cross slide) by maybe 0.05mm per cut and listening to the noise to decide whether I was asking for too much. For this particular job it had the advantage of repeatability - all of the new nuts were cut to the same 'Z' depth. I had the job mounted on some M6 studding with a normal nut locked tight against it - the flats on the nut in the vice jaws then kept the two cuts parallel.
I'd agree that it would be unwise to ask too much of the DB/SL in milling mode. I always find milling rather stressful - I regard the cutter as actively trying to damage itself, the job, the machine and me. Make sure everything is clamped up tight and then go round and check it all again. Re-check at intervals because the vibration can loosen things too.
I also found that climb milling seemed to reduce the volume of the noise so ended up taking all of my cuts in that direction. This seems to be contrary to the usual advice for small machines but that was my experience.
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I have added a drawing to the files - QUILL-SCALE.PDF
This has two possible scale rings that can be used with the quill feed. One is marked 0 - 30 mm in both directions, the other is marked ±15 mm. They can be printed onto thick card and cut out - if the central hole is a snug fit on the handle you can zero them like any other scale ring. I tried this when I had my SL and it works well enough. I intended to print one on acrylic with a laser cutter, but then my SL departed, and I never took it any further. I would have added a springy bit in the middle so it had better grip on the shaft, but taking into account how brittle acrylic is.
Just make sure the print is at 100%, not adjusted for paper size. It's nominally A5 (210 × 148 mm, 8 1/4" × 5 13/16"), so small enough to fit on most standard sheets.
A more thoroughly engineered fitting is possible, and I reckon working to abut 0.1 mm should be realistic. Calculating the markings is easy enough - the rack is 1 mod, so the linear pitch is π, 3.14159 ... and the gear has 10 teeth, so the full circle represents 31.4159 mm (1.237"). The maximum travel is just under one turn of the shaft, so there is no problem with the scale running over 360°.
Thinking about it now, I do still have an SL headstock that needs a rebuild, and I was going to make a new lever for it. Maybe I could do a scale for it at the same time. If so, I'll post whatever I do.
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beetlebud makes a dial indicator
bracket that attaches to the motor mount to solve this problem.
Michael
--
Michael Porter
Michael Porter Marine Design
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I use a 2” dial travel indicator for accuracy in measuring the vertical position of the quill travel. I can precisely position the quill at any point within its travel making repeatable cuts possible and actually quite easy.
Dick
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That sounds good, it would be nice to know if you have any special method for positioning the quill precisely and easily. ?The lever doesn’t give any sensitivity and holding it in one place precisely while re-tightening the quill bolts, is a rather clumsy activity, at least for me.
Regards?
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On 10 Jul 2022, at 12:58, OldToolmaker via groups.io <old_toolmaker@...> wrote:
?I use a 2” dial travel indicator for accuracy in measuring the vertical position of the quill travel. I can precisely position the quill at any point within its travel making repeatable cuts possible and actually quite easy.
Dick
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Mehmood,
Yes, the setting of the vertical quill is a bit fiddle. Some day I will come up with a smoother way to set it, perhaps with a lead screw arrangement.
Dick
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There have been discussions/comments about difficulties aligning the head vertically.? The attached photo shows my current attempt to handle this.? It is based on the use of what are generally called a "flange support for linear guide rail 25mm" which can be found online and at Ebay.? I use 3 of these brackets: top, bottom, and head support.? The threaded rod is 8mm x 1.25 from True Value.? The ends of this 8mm can be just turned down to 1/4".? I tapped a tight bushing for this which is attached to the center flange.? I made a block of aluminum, screwed it to the center flange with two 8x32 screws.? This block protrudes up into the Unimat head support arm, and is fastened with a 10x24 from each side.
Does anyone know of a reasonably priced knob graduated in 50 to use on my 1/4" shaft on top?? Don't tell me to make it.
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I believe Sherline knobs fit 1/4" shafts, you might find used
ones on Ebay if someone has upgraded to ones with adjustable
scales.? Replacement knobs are available from Sherline or Taig for
cross slide, but have not researched prices.
Chuck Daldry
On 8/3/22 10:51, John Hutnick wrote:
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There have been discussions/comments about difficulties aligning
the head vertically.? The attached photo shows my current attempt
to handle this.? It is based on the use of what are generally
called a "flange support for linear guide rail 25mm" which can be
found online and at Ebay.? I use 3 of these brackets: top, bottom,
and head support.? The threaded rod is 8mm x 1.25 from True
Value.? The ends of this 8mm can be just turned down to 1/4".? I
tapped a tight bushing for this which is attached to the center
flange.? I made a block of aluminum, screwed it to the center
flange with two 8x32 screws.? This block protrudes up into the
Unimat head support arm, and is fastened with a 10x24 from each
side.
Does anyone know of a reasonably priced knob graduated in 50 to
use on my 1/4" shaft on top?? Don't tell me to make it.
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Hi
John:
I would
look in my junk box, I do have a 100 graduated dial from
Hardinge.
Then
there is McMaster-Carr:
Or
Misumi:
Or you
could print one on paper or 3D print one.
Carl.
On 8/3/2022 12:51 PM, John Hutnick
wrote:
toggle quoted message
Show quoted text
There have been discussions/comments about difficulties aligning
the head vertically.? The attached photo shows my current attempt
to handle this.? It is based on the use of what are generally
called a "flange support for linear guide rail 25mm" which can be
found online and at Ebay.? I use 3 of these brackets: top, bottom,
and head support.? The threaded rod is 8mm x 1.25 from True
Value.? The ends of this 8mm can be just turned down to 1/4".? I
tapped a tight bushing for this which is attached to the center
flange.? I made a block of aluminum, screwed it to the center
flange with two 8x32 screws.? This block protrudes up into the
Unimat head support arm, and is fastened with a 10x24 from each
side.
Does anyone know of a reasonably priced knob graduated in 50 to
use on my 1/4" shaft on top?? Don't tell me to make it.
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I ordered a 2 1/2"? 1/4" hole? 0-50 graduated handwheel from Sherline.? It is $16.38 + $4 shipping.? At this price, there is no need to be searching and dicking around with anything else.? They also have the smaller handwheels and those with adjustable collars which might be of use to someone here making a project.
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Here is the final work of art with the Unimat head mounted and the 2 1/2" Sherline handwheel installed on the top shaft.? I made a little brass pointer.? With washers under the hand wheel, the head screws up and down fairly smoothly.? I ordered from Sherline on Friday and got the handwheel Monday.
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Despite my dismay at you cutting up a perfectly good Unimat base, I have to say it looks quite good. May you get many happy and productive years of use from it.
Bill in OKC?
William R. Meyers, MSgt, USAF(Ret.)
Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY!
On Tuesday, August 9, 2022 at 02:35:10 PM CDT, John Hutnick <johnhutnick@...> wrote:
Here is the final work of art with the Unimat head mounted and the 2 1/2" Sherline handwheel installed on the top shaft.? I made a little brass pointer.? With washers under the hand wheel, the head screws up and down fairly smoothly.? I ordered from Sherline on Friday and got the handwheel Monday.
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Further to the subject of Unimat milling, here it is drilling a #33 hole 2" deep edge-on in a piece of 5/4x4 lumber.? The head is rotated 180° away from the bed.? The quill is not used - the head is simply cranked down for the full length of the drill bit into the wood.
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Carl
OldToolmaker
Bill in OKC too
