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Mill head tramming

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Martin Shaw 106/01/2019 14:22:25
103 forum posts
32 photos

This is a subject that has probably been done to death, however I thought I ought to measure what my SX2.7 actually is. In the X plane over a 10" span there is a difference of 0.0016", and in the Y plane over a 5" span (the full depth of the table) there is a difference of 0.0008". I recognise that the head is not exactly perpendicular, however are the measured diferences going to make that much odds for the type of general engineering I'm likely to do and also realising that removing the differences is likely to be very time consuming and potentially not greatly improveable.

Regards

Martin

John Haine06/01/2019 14:41:44
2500 forum posts
132 photos

If you think of error over the diameter of a typical cutter they are very small and no worth worrying about I'd have thought. Might start to make a visible difference with a fly cutter or face mill but hot so much as to generally affect the accuracy of what you make.

JasonB06/01/2019 14:43:08
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15338 forum posts
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Should not make too much difference, if you do want to play with it then shims under the column base are the way to do it.

Russell Eberhardt06/01/2019 15:10:50
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2443 forum posts
83 photos
Posted by JasonB on 06/01/2019 14:43:08:

Should not make too much difference, if you do want to play with it then shims under the column base are the way to do it.

Difficult to find shim stock thin enough to correct that sort of error though. His figures seem good enough for me.

Russell

JasonB06/01/2019 15:16:24
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That's how I did the SX2.7 I have in the workshop, 0.0002" over 5" span will do for me.

Ron Laden06/01/2019 15:45:24
1038 forum posts
158 photos

I know mine needs adjusting, just havnt done it yet. Wouldnt I be right in thinking that before any adjustments are made between the column and base the table gibs need to be adjusted to be pretty well spot on or as close as..? Any badly adjusted gibs could have the table high or low or not horizontal from one end to the other or am I wrong..?

David Standing 106/01/2019 16:00:25
1206 forum posts
45 photos
Posted by Ron Laden on 06/01/2019 15:45:24:

I know mine needs adjusting, just havnt done it yet. Wouldnt I be right in thinking that before any adjustments are made between the column and base the table gibs need to be adjusted to be pretty well spot on or as close as..? Any badly adjusted gibs could have the table high or low or not horizontal from one end to the other or am I wrong..?

You aren't wrong.

And before tramming, lock all the axes that you aren't actually reading too.

Tim Stevens06/01/2019 17:38:31
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1019 forum posts

And I suggest that you do any checks with the table in the central position. Especially if your table is on the long side.

Cheers, Tim

Vic06/01/2019 17:41:16
2041 forum posts
10 photos

Given its a lightweight machine it's quite possible it will deflect as much as you're showing when making a cut.

I'd leave it alone, you could make it worse.

Martin Shaw 107/01/2019 11:54:03
103 forum posts
32 photos

Thanks very much for your thoughts, the consensus is that within the limitations of the machine it's probably adequate and doing nothing is the preferred option, I wholeheartedly agree. I drew deeply on the trigonometry of over 50 years ago and have calculated I would need a shim of 0.0012" to correct it, this is almost baking foil, and as Vic has pointed out might well make it worse. Leave well alone if your ahead is just plain sensible. Thanks for the help.

Martin

Edited By Martin Shaw 1 on 07/01/2019 11:54:42

mechman4807/01/2019 18:23:58
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2365 forum posts
373 photos

For those sort of readings... 'If it aint broke don't fix it'

George.

Ron Laden07/01/2019 19:29:27
1038 forum posts
158 photos

Martin, I think if I had a reading of 0.0016" over ten inches and 0.0008" over 5 inches on a new machine straight out of the box I would have considered it spot on or as near as. To be honest I wouldnt have expected that it would be good to know if Jason had similar figures with his.

Ron

Ron Laden10/01/2019 08:51:16
1038 forum posts
158 photos

Adjusted the 3 gibs on the mill this morning its had a fair bit of use in the weeks I have had it so it was worth doing. Trammed the mill and it wasnt good but I expected that, 0.0035" in X and even worse 0.005" in Y. Shimmed the column with cut pieces of feeler gauge, it only took 2 pieces one on each rear corner as the column was leaning backwards. I found that you calculate what should correct the error but in reality it doesnt work like that or at least it didnt for me and it took a bit of trying different thickness of shim to get it right.

Good now, 0.0012" over 8 inches in X and 0.00025" over 5 inches in Y.

Michael Gilligan10/01/2019 09:05:28
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13059 forum posts
570 photos
Posted by Ron Laden on 10/01/2019 08:51:16:

Good now ... 0.00025" over 5 inches in Y.

.

Is that a typo, Ron ?

... or did you get a spectacularly good result ?

MichaelG.

JasonB10/01/2019 09:11:04
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15338 forum posts
1580 photos

Does that make my 0.0002" over 5" even more spectaculardevil

Michael Gilligan10/01/2019 09:18:08
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13059 forum posts
570 photos
Posted by JasonB on 10/01/2019 09:11:04:

Does that make my 0.0002" over 5" even more spectaculardevil

.

No, Jason

I was just asking Ron a straight question, based on the apparently massive improvement made by simple means at the hand of a relative newcomer.

MichaelG.

Ron Laden10/01/2019 09:33:35
1038 forum posts
158 photos
Posted by Michael Gilligan on 10/01/2019 09:18:08:
Posted by JasonB on 10/01/2019 09:11:04:

Does that make my 0.0002" over 5" even more spectaculardevil

.

No, Jason

I was just asking Ron a straight question, based on the apparently massive improvement made by simple means at the hand of a relative newcomer.

MichaelG.

Michael, thats what the dial gauge is telling me, its almost spot on and I checked it 3 times. Dont know if I have just been lucky but why shouldnt it be that good..?

Ron

Michael Gilligan10/01/2019 09:39:59
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13059 forum posts
570 photos
Posted by Ron Laden on 10/01/2019 09:33:35:

Michael, thats what the dial gauge is telling me, its almost spot on and I checked it 3 times. Dont know if I have just been lucky but why shouldnt it be that good..?

Ron

.

Thanks, Ron yes

As I said ... it was just a straight question.

You improved from 5 thou to 2.5 tenths of a thou, with some simple shimming.

Well done you.

MichaelG.

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