DRO installation - mounting holes

Hi,

My DRO kit will arrive soon, I've been scouring the internet looking for tips.

Trying to get my head around things, I'm a little concerned about making the mounting holes in the column and table to accept the scales etc. I'd appreciate any tips for getting accurately positioned holes ready to tap - the only way I can think of going about this is to use a hand drill.

Could I make a simple drill guide that could be held in postion with a clamp - or do I just make a centre pop?

Thanks,

Mike.

I did mine with a pop mark and cordless drill. Most of the mounting plates have slotted holes so as long as your are not wildly off there will be enough adjustment.

J

Edited By JasonB on 25/02/2012 20:15:33

Mike

I doubt its worth going to the trouble of making special drilling jigs or guide. I used a hand held pistol drill and started with a 1.5mm pilot hole then increased the drill size until I got to the tapping size needed. The main thing is just to be careful and take your time. I actually used a 3/16" Slocumb bit in the drill and managed without centre punching.

Ultra precise positioning should not be needed if you use an oversize hole or slotted bracket with a washer.

Ian P

Cheers fellas.......I'll charge the battery drill up then!

Thanks,

Mike.

Hi Mike,

When I installed my DRO on my mill, I found that the slots in the scale ends were sufficient for getting the scales aligned one way. However, the surfaces that the back of the scales contacted were not anywhere near flat or aligned to the axis of movement. I dealt with this by fastening one end of the scale, checking alignment, and adding shims of thin sheetmetal to the ends as needed. I made these as rectangles with a slot in the middle of one side to the centre of the rectangle, so the shims fit over the screws and stay where they are supposed to be. On one end of one scale, the shape of the casting on the mill where the scale was to be attached was very irregular. To deal with this I made a sub plate of 1/8" steel to fasten to the scale, and a hole all the way through to the casting for a permanent through-screw. I got the scale in place, aligned it, and packed epoxy putty in behind the sub plate to fill the gap and stabilize the plate. This putty comes in a roll shape, with a grey resin outside and a black resin inside. One brand is Devcon, Loctite also have one. You tear off a wad and knead the two coloured resins together and they will harden like rock, in about a day, without shrinkage. the putty can be filed sanded and painted to match the castings afterward. Be sure to wear rubber gloves for the mixing or you will have dark grey fingers for a few days. (don't ask me how I found that out). This putty is also excellent for filling errant drilled holes in used machine tool tables just FYI, as well. Hope these ideas help if you have similar issues.

JD

Assuming its the proper scales these will have a backing with elongated slots. Nothing easier just hold backing with one hand, use the 4.2 drill straight in no marking or punching. Tap the hole, nip up and centre/align this backing then drill next one.

My Harrison i didnt have to shim the X or Y and Y1 axis, its British. Theres more bend in the supplied extrusion, in fact 7 thou.

The problems you will have and will take time is when special mountings are needed and may be when drilling holes to line up with existing tapped holes.

If you are using the cheap scales, the reader backing where tapped to accept the supplied flimsy worthless bracket could take some doing without a dro but a necessity for any accuracy. Done it 4 times.

Hi all - thanks very much, I'm itching to get cracking now!

I've not actually selected the scales yet. The standard ones are Easson GS10, and I'm thinking of choosing GS30 slimline scales instead (mainly as I'm planning to install the X axis scale on the rear face of the table so that my power feed limits and auto stop switch aren't afffected -so the thinner scale will mean me losing less travel).

I'm just awaiting an answer from the seller re. what type of covers are included.

Thanks,

Mike.

Hi Mike if you are mounting the scale at the back of the table make sure you put a stop in place so you don't crunch the scale between the table and the colunm.

Paul

Hi Paul,

Yes - I'd thought of that but thanks for suggesting it as it would be an expensive and regrettable mistake!

Thanks,

Mike.

Hi,

I'm new around here. I have a Harrison 11", and would love to fit DRO but have no idea where or how to drill holes. I have absolutely zero precision of eye, which is why I use tools! and am afraid of drilling holes in my machine that would, if I got it wrong, make it next to impossible to fit the DRO. Does anyone have specific experience of fitting DRO to this machine? What scale lengths do I need?

Please bear in mind that I am not very good at this - I've hed to pick uip what I could without much help and have problems understanding all sorts of stuf the cognoscenti take for granted!

Martyn Stevens

If one makes the connection between the pick-up and its mount via a 'J' shaped piece of springy shim, then that allows for a degree of misalignment and slack (up and down, left and right) in the system, without compromising rigidity where it's needed.

Martin.

Martyn a warm welcome, i never got round to fitting a proper DRO to my old Harrison.

I can check later because i bought the X scale for the larger mill and if wrong might have just scraped in on the 140 same lathe but newer squarer head stock.

The Y axis is the problem without causing undue agravation bt installing in front or behind the Y axis cross slide like so many other, iy gets in the way. For this i was going to mount outboard at the rear, a tight fit just clearing the splash tray wound in, think 200mm rings a bell. Of course wasted length has to be added on at both ends then add wasted length of C type covers and wasted unused scale length. Before you know it 5" may have to be added. Of course this would be a long winded job and need bracing up, or the swarf will interfere when built up.

However, there is an easier way, use the magnetic, no wasted length just buy or cut to what length is actually needed. Done on my M300 Y axis, tail stock and coventional type on X axis dead simple its British. I will be surprised if you have to shim more than a thou over the X travel!