Anyone come across a stuttering problem on a Thermwood 67

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Mark Angus
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Anyone come across a stuttering problem on a Thermwood 67

Postby Mark Angus » Fri, Jul 06 2007, 2:58PM

Hello

The company I work for bought a second hand thermwood 67 5 axis router. The problem we are seeing is a stuttering along the y axis (table) during test cutting through \"air\" , not smooth like I imagined it. I use Visualmill from Mecsoft, but the previous operator used Alphacam and apparently had the same trouble. The machine has hardly been used because of it. I cannnot believe its the software as I have used it on 3 differnt machines without any trouble.Maybe its because it is an old controller, running on OS2 warp ?

Mark :?:

Mark Hesketh
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Postby Mark Hesketh » Mon, Jul 09 2007, 6:11AM

we run a thermwood 45, but we sometimes see a \"wobble\" as it moves in the y-direction if the drive-screw supports along the side of the table do not fully extend. The gantry moving at high speed will then cause the screw to bounce, which causes the bit to wobble. This only happens when those supports decide to stop supporting though.

Don't know if this is even close to what you were talking about, but hope it helps

Ryan Hochgesang
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Postby Ryan Hochgesang » Mon, Jul 09 2007, 8:17AM

Hi Mark,

This is likely due to the way the code is posted from your CAD/CAM system. There are a couple of M&G codes used to smooth machine motion which are outlined in the Thermwood machine programming manual. As a general rule, it is best to design geometry in CAD system using arcs and straight lines. When using splines or polylines, the small segamented code could create a choppier machine motion. The two M and G codes that are helpful to smooth machine motion are:

- G09F# (Tangency Factor, Usually 8 is the best value, Range from 1-15)
- G8## (Acceleration factor, Usually 2-3 is best, Range from 1-9)

These codes are typically put in the header of the cnc program so that entire program runs under specific value. However, you can alter throughout program by simply changing value.

I hope this information has been helpful.
Ryan Hochgesang
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Michael J Starry
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Postby Michael J Starry » Mon, Jul 09 2007, 1:19PM

Grease and oil!! We have a couple machines that do this as well, and aside from the codes Ryan mentioned, we have found that adding grease and oil, including a very thin coat hand applied to the rails and screws, will generally solve this problem.

Mark Angus
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Thank you

Postby Mark Angus » Tue, Jul 10 2007, 7:07PM

Many thanks to
Mark Hesketh,Ryan Hochgesang and Michael J Starry for all your replys. the problem was solved with the G code.- G09F# (Tangency Factor, Usually 8 is the best value, Range from 1-15). Finally after 4 years Asylum might be able to use the 5 axis Thermwood. I joined them 8 months ago and made it my goal to get it going.

I will take Michaels advice and grease and oil the machine.

Mark


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