Sudden Z drop

oyoung · Post by **oyoung** » Fri 17 Oct , 2014 17:48 pm

Hi - I am having a problem where the Z value jumps down about 4mm seemingly at random.

I am using a 1mm ball nose cutter, with a tapered shank. I am aware that if the shank fouls the workpiece a Z jump can happen, but it seems to be continuing. The enclosed photo shows the beginning of a cut showing the dramatic stepdown, despite restarting the Novamill. Please help?

Martin · Post by **Martin** » Fri 17 Oct , 2014 18:44 pm

Can you try running "Denford Machine Firmware EasyUpgrader" to check the NextStep card is up to date. You can download it from,

https://website.denford.ltd.uk/index.php ... -downloads

oyoung · Post by **oyoung** » Mon 03 Nov , 2014 15:37 pm

Hi, finally managed to do your suggestion, thanks. All drivers are up to date.

Problem still ongoing, seemingly at random. Any more suggestions?

Martin · Post by **Martin** » Mon 03 Nov , 2014 22:54 pm

Several things you could try/check.

Make sure you are running the latest version of VRMilling.

Have the slides been oiled?

Check for ware on the gib strips & adjust.

Check for backlash & adjust.

Try running without Turbo on.

oyoung · Post by **oyoung** » Tue 04 Nov , 2014 14:47 pm

Thanks again. Slides are well lubed, and gib strips working well. No backlash, and running VR Milling 5.49.0.613.

I have noticed that the VR Millling software registers the tool 3mm below the surface, but it is actually 8mm down. If we suppose that the PC and the Mill are ok, then it suggests that the Mill Control Box is faulty. What is the most likely issue? How much would that cost to rectify?

Thanks

Martin · Post by **Martin** » Tue 04 Nov , 2014 17:53 pm

Can you try running the program at a slower feed rate? It still sounds like it is stalling for some reason when it lifts up.

oyoung · Post by **oyoung** » Tue 04 Nov , 2014 22:17 pm

Hmm.. some success. Tried your last suggestion about turning off the turbo, and it seemed to work fine.

I have been cutting similar jobs at full speed for, well, years now. Why is it suddenly going wrong? I have tried a *.fnc file that I made in Summer, and that was ok, it just seems to be files that I have made since September. The puzzle is that nothing has changed. Any ideas? I don't really want to have to slow these cuts down if I can help it.

Thanks again.

Martin · Post by **Martin** » Wed 05 Nov , 2014 2:38 am

This may help,

viewtopic.php?f=41&t=1467

oyoung · Post by **oyoung** » Tue 11 Nov , 2014 9:35 am

OK - so it seems the old girl is getting on a bit, and she can't cope with the rough-and-tumble of the turbo any more.

Let's hope that slowing down gives a new lease of life. Thanks for your help!

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Sudden Z drop

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