Parallelogram misalignment problem.

Hi guys,

I was asked to cut some holes for a bakery display unit to hold cup cakes and make a rectangle release cut then some without the holes for underneath. I was disgusted to find (after making 20 of them!) that they came out as parallelograms! Thankfully fixable on the table saw and the holes were not too misaligned that you would notice but I obviously have some problem.

My guess would be a slight error on the motor tuning in mach3.

Has anyone had a similar problem before that could shed some light on it please?

When I calibrated my motors I used the manual method of telling it to cut 100mm then calculating from the actual cut length. I suspect that there may be a better way to do this.

Any help would be greatly appreciated!

Thanks,

KC

Kevin,

are your x and y axes square?

Hi Komatias,

I measured the squareness of my gantry and there is a problem. there is about 2mm of difference across the diagonals.


Is this something that can be compensated for in software or do I need to fix the machine?


I'm using a 6040 Chinese eBay machine.

Thanks,

KC

No, software will not compensate for out of square. But it is not difficult to fix.

If the machine is anything like my little 3040, then you could loosen the screws on the bed and gantry and bring it into square. Use a good engineers square to true everything up and then tighten the screws back up slowly checking your alignment every so often.

With the ebay stuff they probalby have been banged about on the trip from China so we have heard a number of cases on here with them being out of square. Some have advocated the hammer approach but I am more in favor of a subtle approach.


Every machining workshop should have a good engineers square, if you do not have one then I am sure you can pick one up pretty cheap from your equivalent of "Machinemart"

Komatias,

Thanks for this,

It sure is reassuring to hear how others dealt with this problem before reaching for the sledgehammer!

My engineers square is what I used to establish where the problem is.

I will try the screw-loosening approach first.

I'll let you know how I get on!

I am a couple or 3 weeks away from moving premises so I may wait until then before attempting the fix.


Cheers,
KC

Well that didn't work! :mad: Lol.

I tried loosening the screws and pulling it into alignment but I have had no luck yet.

I cant figure out how to measure it accurately. I tried using the engineers square and it seemed to be misaligned and then it looked square after the attempted fix but it produced the same problemelogram.

Measuring the diagonals seems a bit inaccurate as the aluminium extrusion can move in relation to the tracks when the screws are loose.

I tried a couple of different times and I see no change in the problem so I must be doing it wrong or maybe this is not where the problem is.

Stripping it down, twisting it, rebuilding and making a test cut take a long time too!

Could someone recommend a better method and/or tools?

...Or any suggestions at all.

Thanks again,

Kevin.