Lathe DRO

JimDawson

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Last weekend my son informed me that it is time to put a DRO on the lathe. I guess he hasn't figured out what all those little numbers are for on the dials. :rolleyes: He has a short production run for a product he is developing so figured it would be easier to do it with a DRO. I suggested we just CNC the lathe, but he thought that would be overkill and make the lathe less useful. Mmmm OK. :confused: He's buying the DRO so we'll do it his way, I'll just spec it so it will be CNC compatible later.:p

So this is the starting point. A basic Jet 1340GH.
upload_2017-4-14_18-20-24.png


Since I have been experimenting Ditron products, I ordered one of their D100-2V readouts
upload_2017-4-14_18-23-6.png


And 2 of their DMR-200, 1um read heads, and 2 meters of magnetic tape. Should have all the pieces by Wednesday of next week.

See the test results of the DMR-200 read head here http://www.hobby-machinist.com/thre...le-replacement-vendor-spec.49299/#post-475210

Hmmm, does this mean that I can have 1 micron accuracy on my lathe now?;) Nah, I suppose not. Durn.:(

I have never liked the idea of scales being exposed on a lathe, especially the cross slide scale, but have never seen a better way of doing it. Can't put it on the headstock side, it would be destroyed by something in no time. If you put the scale on the tailstock side of the cross slide, you lose some working clearance. Not acceptable in my book. I want the scale tape and read heads well protected and out of the way.

There is a better way.....I just haven't designed it yet.:grin: Stay Tuned..........

upload_2017-4-14_18-25-10.png
 
You'll like the DRO on your lathe, not as "essential" as one on a mill, but still nice to have. Have one on my Grizzly G0709 lathe and turn it on maybe 10% of the time; obviously depends on the work being done. I use the DRO on my tail stock quill all the time, easier than doing the math.

Bruce
 
I don't understand why the scales need to be so large in general. You would think someone could produce a very small dimension scale that could mount on the cross slide and take up minimal space.
Robert
 
Deciding on the least obtrusive mount for the cross feed scale was my problem too.

I had considered mounting the scale to the rear of the cross slide but that would have meant losing the back splash. Another idea was to use a spring steel tape riding on a ball bearing guide to turn the direction of motion parallel to the ways. The steel tape concept has been used effectively for precision positioning requirements such as hard drives. You could use a tension spring to keep the tape taut or run it around in a loop. I would think that spring from a small pocket tape rule would work.

In the end, I decided to go with the more compact iGaging scales and mounted the scale on the tail stock side of the cross slide with the pickup mounted below and between the ways. I lost about an inch of travel on the tailstock but felt that it was the best compromise.

The write up on my DRO install is here: http://www.hobby-machinist.com/threads/another-lathe-dro-install.34106/
 
I don't understand why the scales need to be so large in general. You would think someone could produce a very small dimension scale that could mount on the cross slide and take up minimal space.
Robert
You would think so, Robert. Unfortunately, the industrial side of their business has larger machines where mounting is a problem. The smaller hobby type machines just aren't a big enough market to mess with, IMO. iGaging has made an effort in that regard but their pickup could be smaller too. Their scales have 10 micron resolution. I'm not sure that their pickup would be robust enough to be able to resolve 5 microns, let alone 1 micron.

There are other technologies that would be amenable to small scales with higher accuracy. An interferometer comes to mind. It uses a beam of light and can resolve to better than .1 micron. Sounds like a good project for some entrepreneur.
 
I don't understand why the scales need to be so large in general. You would think someone could produce a very small dimension scale that could mount on the cross slide and take up minimal space.
Robert

They don't have to be.

That is one of the reasons I went the way I did on this install. The mag tape is only 0.063 thick, and the read head is 1.2 x 0.95 x 0.39 inches. All you need is a surface to stick the tape to, and a place to mount the read head. I have 1 micron mag readers on 3 machines (soon to be 4) in my shop, and am very happy with the performance. I nearly have the read head mounting design complete and it will not be visible on the lathe at all. I may get it built this weekend.

What I would really like is a heads up display. The problem with a DRO on anything is you normally have a choice of looking at the DRO or the work. I want to see both at the same time.:grin: Time to start thinking about that one. Ideas anyone????? :eagerness:
 
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The Touch DRO comes a little closer to the heads up as I can place my smartphone anywhere. If I make a mount for a Noga system, I could put the display wherever is convenient.
 
I know how to build the HUD, but not how to do it in the hobby class price range. But, I haven't researched all of the new hardware available, some of the stuff out there is pretty cheap.
 
Jim- I missed that about the tape thickness. Yes, that would help a lot. I wish the read head wasn't .095" That is the issue on my machine.
Where would you ideally project the HUD image? I guess just above the work piece?
Robert
 
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