Accuracy

[CNC Router User Man (Unregistered Guest)]

Just a few minutes ago, I cut two arcs in MDF from the same Artcam drawing, one inside cut, one outside cut. The two pieces don't mate perfectly... there are slight gaps along the 30" arc length (18" radius), some small, and some as big as 1/32". I am using a porter cable router in a non-alpha PRT.

What do you think this inaccuracy can be attributed to? The non-closed loop motors? Deflection by the router and bit? Overall slight inaccuracy of the machine?

It's not too big of a deal at this point in time. This PRT is just a "starter" machine for me that I bought mainly to see if a CNC would be the right tool for my shop. In the future, I would like a machine that can cut the parts dead-on. What kind of a machine can do that for me? I understand that a Komo Mach One could probably do it, though I'm looking at a $135K price tag (can you say business loan?). Would a Techno or Multicam router offer the kind of accuracy I'm seeking?

[jay]

Obviously something is not right. A well tuned PRT should cut as instructed. Funny but when I first got my PRT I would start off thinking it was a machine error but it always ended up being an error made by the dumb or uneducated operator, ME.

Need more information. Post the art file or email it to me (go to my profile for email address). Lets see exactly how you set up the cut. If perfect we can then start to check out the different part of the machine that may need tweeking.

Cheers, Jay

[robtown]

Sure that KOMO can do it. It can also relieve you of 3600.00 a month. Your PRT can do better than that. Get out the spirit level and a good straight edge and spend a day checking to make sure if it's square and level, check your v rollers and all bearings to make sure they are tight, make sure your Z axis is spot on plumb, and your rails are parallel.

What softwares did you use to draw your parts? Corel is a good layout proggie, but lacks accuracy when exporting to DXF ( Illustrator too).

[Randy the macho man savage (Unregistered Guest)]

Are the Arcs nice and smooth or do they seem to be alot of small straight lines? I would check to see if you x car is square and how your hold down bearings on your y car are acting. What about how you are holding your material down. In the beginning I was having some problems with what I thought was the bot...but it was actually the way I was hold the material down.

[gene_marshall]

sounds like the gantry is out of square to me

[ron brown]

Could be something like arc length not set properly too. One post, no follow up - unregistered.

Ron

[gerald_d]

...6 weeks ago....dead thread.