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Phil H114/07/2020 20:16:47
290 forum posts
28 photos

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.

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Mark Rand14/07/2020 21:26:18
899 forum posts
5 photos

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?

Martin Connelly14/07/2020 22:00:54
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1399 forum posts
164 photos

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

Martin C

Ady114/07/2020 22:54:57
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3734 forum posts
519 photos

Now be honest

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

David Noble14/07/2020 23:04:34
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188 forum posts
8 photos
Posted by Ady1 on 14/07/2020 22:54:57:

Now be honest

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

Quite agree. Nice one

David

Phil H115/07/2020 09:33:52
290 forum posts
28 photos

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

SillyOldDuffer15/07/2020 10:03:47
5924 forum posts
1281 photos
Posted by Phil H1 on 15/07/2020 09:33:52:

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?

...

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

Brian H15/07/2020 10:20:49
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1675 forum posts
109 photos

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

Oven Man15/07/2020 10:33:50
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59 forum posts
6 photos
Posted by Ady1 on 14/07/2020 22:54:57:

Now be honest

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

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

Phil H115/07/2020 10:45:52
290 forum posts
28 photos

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

Bazyle15/07/2020 13:00:58
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5290 forum posts
201 photos

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.

Phil H115/07/2020 13:11:09
290 forum posts
28 photos

Bazyle.

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

Phil H

Phil H115/07/2020 15:04:07
290 forum posts
28 photos

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

Baz15/07/2020 15:41:39
409 forum posts

Chinese quality strikes again!

Phil H115/07/2020 16:34:30
290 forum posts
28 photos

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

Bazyle15/07/2020 18:14:31
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5290 forum posts
201 photos

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.

Michael Gilligan15/07/2020 19:02:40
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15871 forum posts
693 photos
Posted by Baz on 15/07/2020 15:41:39:

Chinese quality strikes again!

.

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

MichaelG.

Neil Wyatt15/07/2020 19:41:42
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Moderator
17970 forum posts
709 photos
77 articles
Posted by Phil H1 on 15/07/2020 16:34:30:

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.

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

Phil H115/07/2020 19:56:42
290 forum posts
28 photos

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

Phil H116/07/2020 13:25:14
290 forum posts
28 photos

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

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