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Old 10-19-2016, 09:33 AM   #31
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J,

In my opinion, fitting DRO's to a model engineering machine has been one of the main steps forwards in home machining in a long time, just like fitting 3phase motors and VFD's to give infinite speed control.

Unlike what a lot of old timers think, it isn't cheating, as all it is doing is superceding earlier mechanical methods of measurement.

I have been using DRO's since the mid 80's when I was working in a model shop making prototype hard disk drives, and without them at that time, it would have been almost impossible to make to the tolerances required by just jigging and fixture holding, you would have to have made a jig or fixture for each machining operation.
You could now do it with just a couple or three datum points from the bolted down piece part.
I just couldn't wait for the model engineering fraternity to catch up.

When I upgraded my mill system to 3 axis, I had a spare 2 axis display head, so it was only logical to fit it onto my lathe, which already had 2 axis on there. This was at a time I was using my shop as a precision machining area, and those two extra displays made all the difference to what could be achieved.
Try to make a hundred of these steam control valves with some internal tolerances of 2 tenths. This was easily done with my lathe DRO's.





I suppose eventually four axis will become readily available for mills and lathes, until then, we have to take whatever is available. There are already 4 axis display heads out there. Maybe we can do away with scales on our handwheels eventually, I haven't had to use mine for years.

Four axis on my mill, the small one on top is a display head for the scale type I use on the quill and it doesn't require batteries as it runs from a specially designed PSU that a friend made for me.



Display heads on my lathe



The two extra bits that aren't normally fitted

Topslide



Tailstock



Please excuse the junk in the background, that is my spraymist system that had to be got out of the way while I did the DRO mods.


John


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Old 10-19-2016, 10:11 AM   #32
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Bobwho,

"I see DJP mentioning caliper as opposed to scale, calipers are tough... and I never thought much about a scale on the tailstock, just too bulky."

I wasn't referring to a glass scale, I was referring to the cheapo SCALES some people fit, which are the same as the digital scales you use for measuring.

When they are put into a stressed situation, like being twisted, they can have a dramatic failure rate. I know this because I spent a small fortune trying to keep them running on my old mill, I had to have a couple of new or repaired scales sitting in my cupboard all the while they were fitted. It was a godsend when I started using glass scales on my then new machines.

Glass scales are no more tolerant, if you can't mount them totally stress free over their whole range of movement, it is not worth bothering trying to fit them.
I have 7 glass scales (soon to be 9) and one cheapo scale fitted to my equipment and I have yet to have one even flicker with discontent purely because I took the time to mount them correctly with absolutely no twist or deviation over their whole length of operation. It takes lots of time and effort to do it like so, but it is time well spent rather the "throw it on there and if it works, it's done" brigade.
As far as I am concerned, it might not be a few months or even a couple of years, but it will show up bad workmanship in the end.

I might be a bit paranoid over things like this, but I do know that of all the machinery in my place since it was upgraded to mainly all new some years ago, none have never failed me, except when it was a manufacturing fault, one bearing failure (10 minute replace job) and one motor failure (new motor sent out for next day).

BTW, on your glass scale fitment, that is where you should have used a slip joint on you bottom fitting as I did on my tailstock fit, it is the only way to rid yourself of the twisting motion while still retaining your measurement accuracy.

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Old 12-19-2016, 11:29 PM   #33
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Quote:
Originally Posted by rodw View Post
I've fitted a 2 axis DRO to my AL320G. I went with Ditron and am very happy with the quality. The price was pretty ridiculous.

The cross slide was a bit fiddly but worked out nice.









The long feed was easy, made mounting blocks with a slight angle on them and included a setscrew to level the mounts in case I got the angle wrong. I did not use any of the included mounting hardware.
Rod, new chap here. I also have an Al-320 G- L141 and would like to fit a2 axis DRO. It's like buying milk "too many choices". Anyway after looking at your installation my lathe maybe a bit different as there is oiling points and adjusters on the tailstock side of the cross feed. Was this an issue with your installation ?
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Old 12-20-2016, 01:03 AM   #34
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Quote:
Originally Posted by rodw View Post
I've fitted a 2 axis DRO to my AL320G. I went with Ditron and am very happy with the quality. The price was pretty ridiculous.

The cross slide was a bit fiddly but worked out nice.









The long feed was easy, made mounting blocks with a slight angle on them and included a setscrew to level the mounts in case I got the angle wrong. I did not use any of the included mounting hardware.
Not sure what I done before but unable to get my message so will try again.

Rodw, new chap here. I also have an Al-320 G- L141 and would like to fit a2 axis DRO. It's like buying milk "too many choices". Anyway after looking at your installation my lathe maybe a bit different as there is oiling points and adjusters on the tailstock side of the cross feed. Was this an issue with your installation ?
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Old 12-20-2016, 06:00 AM   #35
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Kpar,

You raise a very good point about items being under the read head.

When my lathe was new, it was supplied with the read head already fitted and it covered up the gib locking screw, which is definitely required if taking heavy cuts.
Luckily, my lathe has tapered gibs so those didn't come into equation, just the locking screw.

This post shows how I got around the problem, and can be used anywhere a locking device is required on a dovetail slide.

http://chestermachinetools.forumchit...pid=1286083315

John
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Old 12-20-2016, 09:34 AM   #36
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Quote:
Originally Posted by Kpar View Post
Not sure what I done before but unable to get my message so will try again.

Rodw, new chap here. I also have an Al-320 G- L141 and would like to fit a2 axis DRO. It's like buying milk "too many choices". Anyway after looking at your installation my lathe maybe a bit different as there is oiling points and adjusters on the tailstock side of the cross feed. Was this an issue with your installation ?
Kpar
Sorry for ignoring you Kpar, some of us work for a living. Yes I need to remove the cover to get to the oiling points but I watched the placement of everything so i could get to them. Every time I tke the cover off, I think of leaving it off, but its only 2 scews so I pop them back in.


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