What size DRO on SPG 2217 - BF20 Mill

Hi

Can anybody help me solve a bit of a mystery.

I want to fit DROs to my X and Y axis on my SPG 2217 mill

From what I have found out in the manual the maximum X axis is 565 mm on the Y axis it is 220mm.

From what I have worked out I need a 600mm linear scale for the X axis

and a 250mm for the Y axis./

Is this correct or has anybody else got any suggestions or advice

Thanks

Neil

http://www.southshields-weather.co.uk

Neil,

Machine DRO have a measuring guide on their website.

Stuart

You need the measurement length (not the overall length) of the scale to be at least equal to the maximum travel of the table in that axis. In practice, if they are exactly equal, mounting the scale will be a bit finicky since you'll have to exactly match the scale/table travel at each end.

In practice you need a bit more scale travel than table travel .... the more the better up to a point but that will be limited by considerations of how you will mount the scale (remembering that the overall scale length may be quite a bit longer than its measurement length). The other part of the trade off is, of course, cost. Longer scales cost more. Scales also usually come in discrete length increments.

The lengths you have suggested (assuming they are scale measurement lengths and not overall lengths) sound about right. However, don't take the manual's word for the table travel - measure it yourself.

That sounds a bit tight to me. on the X axis you would only have 35mm and just 30mm on the Y axis to fit the read head and two fixing points without any allowance for the scale not being perfectly placed to use all the available travel.

For my chinese scales the read head is about 40mm long, and allow a good 20-30mm for each fixing point, so up to 100mm extra scale length needed.

Neil

You can often accommodate that by building a "jog" into the bracket that attaches the slider .... effectively centralising the scale. But I agree, if those lengths have to include the end fixing points, they are too small. That's not clear to me in the OP.

The working length of the scales should be longer than the maximum travel of the mill. If the scales bottom out they could be damaged.

Paul.

Hi Neil

I have only just seen this thread.

I have just DRO'd my SPG 2217 III

These are the sizes I fitted to mine

I got them from Arc Euro Trade ( No link To them I am just a satisfied customer )

Bob

<edited to stop table going off to the right>

Edited By Neil Wyatt on 04/06/2015 20:49:30

Hi Neil

I have fitted similar dro's to my VM 16 as Bob; but I have the scales that have remote readouts as opposed to having the 2 axis display unit... in the similar lengths... ArcEuro #.... 8" & 24"

100-061-00200... 8"

100-061-00500... 24"

http://www.arceurotrade.co.uk/Catalogue/Measurement/Digital-Readouts-with-Dedicated-Remote-Display

So far both have served well for my needs & the cost is reasonable... See my pics in my album... 'DRO' ...for fixings.

George.

Edited By mechman48 on 04/06/2015 10:13:31