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Old 02-01-2015, 06:48 PM   #1
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Default How to combat crabbing

I take delivery of one of these mills tomorrow

http://www.arceurotrade.co.uk/Catalo...-HiTorque-Mill

This one has a very rigid cast iron column designed by Arc Euro and sold by LMS in the US, rather than the wobbly tilting one available everywhere else.

Now most people do the CNC conversion of the Z axis on this type of machine by mounting the leadscrew on one side of the head, which if not careful could lead to 'crabbing', that is tilting slightly because of the pull/push being on one side rather than in the middle.
No problems setting everything up, but has anyone done or know of a conversion of one of these "heavy duty" machines where the leadscrew is in the middle of the head rather than to one side, or do I have to work it out myself? I would prefer NOT to have the leadscrew sticking up in the air as they do with the gas struts they do for taking the weight of the head on manual machines.

John


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Old 02-01-2015, 07:23 PM   #2
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Yes I have done the conversion of the X2 with the z in the center of the head. I used the plans from hossmachine. The plans are free to download. Just google him and he pops right up. The man is the king of bench top mills lol.


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Old 02-01-2015, 07:50 PM   #3
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Neoinnj,
Unfortunately, that conversion isn't on the same heavy duty column that I mentioned, plus, they have the leadscrew sticking up in the air, which I am trying to avoid.
If there is no other way, then I will most probably have to follow that lead.
I will have to wait for the mill tomorrow and see what can be achieved when I get my grubby claws on it.

No rush, I was just hoping.

John
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Old 02-01-2015, 08:49 PM   #4
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You will not be disappointed I had one for about six months just finished fit Dro to all 3 axsi quite pleased only had to drill 2 Five mm holes ,the lot comes off in 5 minutes and it doesn't look as if it's done a tour of Iraq happy chipping
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Old 02-01-2015, 08:51 PM   #5
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Quote:
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You will not be disappointed I had one for about six months just finished fit Dro to all 3 axsi quite pleased only had to drill 2 Five mm holes ,the lot comes off in 5 minutes and it doesn't look as if it's done a tour of Iraq happy chipping
I notice you covered the "head" the track must be covered also
to be 100% trouble free
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Old 02-01-2015, 11:53 PM   #6
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Sorry, but unfortunately I am fitting CNC rather than DRO's. This is going to be a plaything to get used to producing the mechanics and using CNC.

For my main mill I use a manual 836 (mini bridgeport) fitted with 3 axis glass scale DRO's plus power feeds all round and my lathe with 4 axis glass scale DRO's. Just about to fit 2 axis high res anti vibration detection glass scale DRO's to my surface grinder. So I am rather familiar to how they work and fit.
I played around with those scale types many years ago and gave them up as a bad job, just too unreliable in general use, especially if you use any type of lube or coolant around them. The amount of money I spent on them would have bought me a good quality set of glass scales.

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Old 02-02-2015, 01:56 AM   #7
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For any interested antipodean readers, the SX2P is sold in Australia by Ausee.

John,
With my old school X2, my plan was always to remove the Z-axis rack but also the hand wheel and shaft and pinion etc, then run the leadscrew down thru the head. It is similar to the hoss version but closer to the column now the rack is gone.... but also now that the handwheel and pinion are gone, the screw would pass right thru the head, fixed bearing at top and at the base and the nut fixed inside the head. This way the leadscrew is not telescoping up and will less likely be a hazard for low flying birds and planes.
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Old 02-02-2015, 05:40 AM   #8
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That sounds like a good solution Simon. I am a great believer in what isn't there can't go wrong, and because the rack will be made redundant by the conversion it will (or might) give the room for things to work how I wanted it to.

Many thanks, definitely an avenue to explore.

John
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Old 02-02-2015, 09:14 AM   #9
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Quote:
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I notice you covered the "head" the track must be covered also
to be 100% trouble free
Yes temporary measure waiting for some uvpc angle to arrive the will cover all 3
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Old 02-02-2015, 09:22 AM   #10
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Theclockworks where did you buy your DRO
I have the same DROs but all of them sometimes add 2-3mm
without moving table i am desperate because i can not rely on dimension.
Maybe i do something wrong ?.
Thank you


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