Could it be? (Avhc .05 off)

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BareWelding619
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Could it be? (Avhc .05 off)

Post by BareWelding619 »

Had a good friend of mine come over to look at my torchmate avhc I kept dragging the material when setting initial cut. He ran a test where the torch will run down contact the material back up to a set height on the avhc and it was .05 closer to the material. So I just added .05 to that .08 cut heigh and it made quite a difference. Is there a way to calibrate the avhc ?
islander261
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Re: Could it be? (Avhc .05 off)

Post by islander261 »

Hi

You have just calibrated your old TM AVHC! Check weekly as the acme nuts and screws wear quite rapidly. I buy my replacement nuts and shafting from McMaster-Carr as they are much cheaper than TM or the new place.

John
BareWelding619
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Re: Could it be? (Avhc .05 off)

Post by BareWelding619 »

In new to this cnc plasma world, is there a right up somewhere on how to calibrate it, I did a quick search but no luck
islander261
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Re: Could it be? (Avhc .05 off)

Post by islander261 »

Seriously, on a TM AVHC you just did the calibration. The reason you had the height error is the backlash in the lead screw. The controller drives the torch down until it hits the sheet and stalls the drive motor. When this happens the acme nut is pushed to one side of the backlash. Then the controller moves the drive motor enough turns the other way to raise the torch to the pierce height. The problem is that the the acme nut needs to move to the other side of the backlash before any actual torch motion occurs. So what you end up with is pierce setting minus the backlash for actual torch travel. With you table off grab you torch and try and lift it, from your description I think you will feel it move about .050", which is the backlash in your screw/acme nut combination. This actually is in the normal range for one of these units, as I recall they recommend replacing the nut and drive screw when the backlash is over .063".

Sorry, I can't tell you exact procedure with out knowing what controller you are using.

John
BareWelding619
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Re: Could it be? (Avhc .05 off)

Post by BareWelding619 »

Do you have any part numbers?
islander261
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Re: Could it be? (Avhc .05 off)

Post by islander261 »

Hello

Here are the lifter parts I buy from McMaster-Carr:
Acme Nut
https://www.mcmaster.com/#95072A128
Acme Screw
https://www.mcmaster.com/#98940A613
Flange Bearing
https://www.mcmaster.com/#57155K324

Each length of shafting will make 3 or 4 finished screws. Just copy the existing shaft if you have a lathe or take it a local machine shop. The part is so simple that they should be able to make all three or four shafts in under an hour.

John
BareWelding619
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Re: Could it be? (Avhc .05 off)

Post by BareWelding619 »

I pulled mine apart on Saturday night finally, my buddy made up a new nut for me works like a charm. Thanks for all the help
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