Need some help, Machine not carving straight lines

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rschaeffer83
Posts: 5
Joined: Wed May 25, 2016 4:16 pm
Model of CNC Machine: Custom

Need some help, Machine not carving straight lines

Post by rschaeffer83 »

I will upload some pictures to give you a better idea of the problem. I thought maybe the angle of the cutter was wrong but when I tried this test it looks like each triangle has something wrong with it. Most of the lines are bowed in and some of the corners don't look right also there was some dog bones while carving a sign earlier.

I am tramming the spindle now and I see that it is .050 off on one side. Could this be the reason for it not carving straight lines or is it something else?

I am hoping you guys can help.

I don't think its a program issue this is definitely a hardware problem. I just changed the spindle out to a smaller one and also made a new and stronger bracket to hold the spindle in place. So as soon as the spindle and bracket was changed I noticed issues.

If this isn't that right section to post in please let me know.

Ryan
Vcarve 1.jpg
Vcarve 2.jpg

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TReischl
Vectric Wizard
Posts: 4567
Joined: Thu Jan 18, 2007 6:04 pm
Model of CNC Machine: 8020 48X36X7 RP 2022 UCCNC Screenset
Location: Leland NC

Re: Need some help, Machine not carving straight lines

Post by TReischl »

You are on the right track.
"If you see a good fight, get in it." Dr. Vernon Johns

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rscrawford
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Model of CNC Machine: CAMaster Cobra 408 ATC, ShopSabre IS408
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Re: Need some help, Machine not carving straight lines

Post by rscrawford »

It could also be that your cutter isn’t the exact angle specified in your tool set up. This is usually the cause of dog bone corners on v-carves.

Draw a thin rectangle and try changing the angle in your cutter set up until you get a perfect cut for the rectangle.
Russell Crawford
http://www.cherryleaf-rustle.com

jsheley
Posts: 19
Joined: Sun Feb 17, 2019 7:27 pm
Model of CNC Machine: expensive_pile_of_junk

Re: Need some help, Machine not carving straight lines

Post by jsheley »

If you have servo motors, then examine the mechanical attachment of the rotary feed-back mechanism for looseness. (guess how I know about this blight!) Also search for slippage or looseness in mechanical transmission between motor and the endmill. Common sources are the shaft couplers and attachments between gears and shafts. Also try slow down feeds and speeds. Excessive speeds also means that your motors will "jerk" the endmill's mechanical transmission during speed changes.

Try the following test:

Tell you machine to make a circle ( say 25mm diameter).
Start with a slow very slow speed.
Make another circle different spot with a faster speed.
Make more circles with increasing speeds up to maximum safe speed.

Look for distortions in circles such as oval formation.

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TReischl
Vectric Wizard
Posts: 4567
Joined: Thu Jan 18, 2007 6:04 pm
Model of CNC Machine: 8020 48X36X7 RP 2022 UCCNC Screenset
Location: Leland NC

Re: Need some help, Machine not carving straight lines

Post by TReischl »

jsheley :

You might want to take a look at the DATE of this thread. Almost a year ago now. . . . . no point in dragging old posts up to the top.
"If you see a good fight, get in it." Dr. Vernon Johns

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