New Toy

For every inch movement of my milling machine X axis via the handwheel, the actual movement is short by 0.015". That is fine for some parts but not so clever if I am trying to make parts like locomotive coupling rods. So as it was quite close to my birthday, I splashed out. Look what I have got.

That does beg the question of how can the feed screw be that far out? Or has the dial a peculiar number of graduations on it?

0.0157" is the difference between 1" and 25mm (to 3 sig figs). Is it a metric machine?

Martin C

Now be honest

You were going to get it anyway 'cos it's fab

Quite agree. Nice one

David

Martin/ Mark,

Your observation certainly makes sense (0.0157" but it definitely states 0.001" on all the dials and it was sold as an Imperial machine. However, perhaps all the Imperial machines are in fact metric but with very poorly executed handwheel conversions? If you look closely at the front plate (it is a bit small on the picture) - even the table has inch sizes rather than metric.

Ady/ David,

I was told ages ago that this kind of conversion would 'change my life'. I am sort of surprised at how accurate the x axis is so far. I drilled two holes in a piece of steel 3.985" apart for my Rob Roy coupling rods and as accurately as I can measure - they are in fact 3.985" apart!!

The kit was very straightforward to assemble and its accuracy (so far) really is impressive. The kit came with some nice aluminium parts and plenty of cap screws but the business end for all three axes is a sticky, bendy magnetic strip thing and a sensor - incredible! It might change my life.

Phil H

Quite common for 'imperial' mini-lathes to have metric lead-screws and rely on the close correspondence between 0.001" and 0.025mm ( 0.000984" ) For close up work, the error is insignificant, the error only shows up when the dials are moved a long way. Much more annoying on a Mill though.

Don't worry about it. DRO on a mill completely eliminates metric vs imperial issues and there are many other benefits. It's hard to understate the value of fitting a DRO to a milling machine - they really are wonderful.

Enjoy

Dave

You definitely made the right choice. I hung my nose over DRO's for some time, having gotten used to having one on a milling machine I used to own.

I bought mine from M-DRO at a show and found them very helpful especially as I was fitting it to an elderly Graham mill/drill. The fitting kit contained everything needed, the instructions were excellent and a 'phoned query was answered promptly and accurately.

Needless to say, I have no connection with the company save as a well satisfied customer.

Brian

You will not regret it. Best thing you can do to upgrade a mill. I got the Z axis option when I upgraded mine, not quite sure how useful it it is as I generally use the built in quill DRO but the X and Y are absolutely fabulous.

Peter

Dave,

Yes I agree, the only reason I noticed it was when I tried to drill the coupling rods at 4" centres. Prior to that, I guess all of my work has probably been hole centres at less than an inch and or 'parts to fit eachother' rather than accurate spacings.

Brian,

Yes the kit is very good. I had to make some T nuts for attaching the X axis but the instructions warn about that and you do have an option to drill instead. I was a bit peeved that I needed to use some of my own M4 screws but when I had finished fitting the kit - guess what I found - yep a bag of M4 screws.

Peter,

The Z axis has also been excellent. I occasionally get a little bit of judder in my Z axis until I adjust the gib (I think that is a feature of this type of milling machine unfortunately). That judder always makes me feel a bit uncomfortable about the Z axis accuracy for spot facing etc. This has solved that issue completely.

Phil H

Now that the possibility of a metric leadscrew has been raised I am all curious as to whether it actually is. I think you owe it to us to move the table 2 'inches' according to the dial and say what the DRO reads. While your problem is solved with the new toy there must be many users of this mill still without one who need to be told of the possible error.

If it is actually a metric screw I thing the vendor owes it to the owners to write to them and inform them.

Bazyle.

Good idea. Ill try it and see what happens. I'll try to report back later today.

Phil H

I tried the measurements and I am still laughing. This is honestly true - I am not proud of this admission but here goes;.

If you read the Y axis dial, it goes from 0 to 0.080" in nice even 0.001" increments.

If you look really carefully at the X axis dial, it is almost an exact copy - but not quite. Going from 0 to 0.070" is fine but you expect the next 10 divisions to take you to 0.080" No - it doesn't. There are 9 divisions!!!! taking it to 0.079"

Using the DRO and comparing - 1" (DRO) = to 0.986 dial (12 revs + 0.040" and 2" (DRO) giving 1.971" dial (a further 12 revs + 0.040".

If I wake up, open my eyes and do it properly I get X axis 1" (DRO) = 0.9986" dial and 2" (DRO) giving 1.994" dial.

Y Axis - DRO 1" = 0.996" dial and DRO 2" = 1.993" dial.

So it is operator error but how ridiculous - a 079" dial!!!

Phil H

Chinese quality strikes again!

At the end of it - it was user error and the accuracy isn't that bad - assuming the Chinese DROs are accurate of course. It is just something that made me laugh. It does work but fancy making a 0.079" per revolution dial.

However, the DRO is a nice toy. No backlash etc. What it has done - almost immediately - is made me think how to make other components in a way that exploits the DRO. Also, previously, I would move to a location, centre drill it, change to a bigger drill etc then move to the next location. I now put the spotting drill in, drill all the positions, change drill and go back and do all the holes because I can simply rewind to the digital readout positions with confidence and speed.

I have also noticed angle positions and PCD stuff. Who knows how I will use that lot.

Phil H

Is it mentioned in the manual? There is nothing on the website to bring attention to whether the leadscrew is metric or that the dial is deceptive.

.

The Chinese often make whatever their customer [i.e. our supplier] wants.

MichaelG.

2mm pitch leadscrew.

It is a metric machine fitted with imperial dials. Odd ones, but imperial dials.

My mini lathe has a 16 tpi leadscrew. So I made a 64-division dial to approximate 0.001" but only use it over short distances as a 62.5 division would encourage false confidence.

Ironically If I had the 1.5mm metric leadscrew, a 60-division dial would be more accurate..

Neil

It really is difficult to complain because it does work - just a bit strange and why does the cross slide (Y axis) work ok?

Anyway, I am now firmly in this century with my digital display. I even got some spotting drills and an edge finder. Whatever next?

Phil H

Bazyle,

Just for completeness, there is nothing in the manual about the leadscrews or handwheels. There is an exploded view and parts list and the leadscrews are simply listed as X axis spindle, X axis nut and Y axis spindle and Y axis nut.

Phil H