Cut Accuracy

Having some issues with accuracy, see photos. One is a “hole” and the other is a part. The part always end up a couple mill small. I would think that even if the size is off (should be 50mm) the 2 cut should b the same…

 

https://photos.app.goo.gl/QhPCGUCpCKzet74J9

If you cut such that the center of the bit is on the line it will give you a part that’s smaller by the bit size. You need to have the bit cut at the outside edge instead of centered. Same thing happen with pockets, except there you need to cut on the inside edge. Estlcam handles all that for you, you just need to ask it to use part, hole, engrave or carve as appropriate.

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You also need to have the bit diameter right. If yoy used a 1/4" bit and said it was 3mm, then it will cut holes large and parts small.

It’s almost certainly a cam issue in my mind. There are mechanical or electrical errors which can affect accuracy, but they are either much smaller or much larger problems.

one is a 50mm “part” and the other a “hole” cam was done with estlecam. the Tool path shows that as well. 3mm endmill, i went to climb milling and now it seems the opposite. The part is to large and the hole is to small.

Are your belts tight?

belts are tight. i ended up getting it although i may have done it the wrong way. my tool is 3mm but i have it set at 2.3mm in estle cam. This give me a part and a hole that end up both correct… I know there is some tool deflection but is this much normal?

That doesn’t seem normal to me. I’m surprised there’s that much flex, but the lines of the square are still straight.

Yes, square and same measurements both on x and y…

Also running with 7mm doc 9mm per sec. Any suggestions are welcome for my feeds. I am cutting 3/4 finished both side ply. Speed is at lowest setting on the 611. I wish I went with the Makita router due to the lower rpm. I have one on order for my mpcnc I am going to build for aluminum milling.

What kind of bit? Running it at the lowest speed seems strange to me. But if it were load, I would still expect to see wavy lines.

Are your pulleys tight on the motor shafts?

Yes I went over everything, standard 2 flute upcut. i figured lower rpm the better. Don’t think these routers go low enough / machine fast enough to get proper chip loading… To fast will just burn the bit won’t it?

IDK anything about proper chip loading. My bits are fine running around 3-5 on the 611.

I generally just keep it at full speed, maybe a notch lower. No smoke so far.

It may be a minor difference but a 1/8" bit isn’t 3mm, it’s 3.175mm your actual bit size may vary but since you’re chasing accuracy this is an important input in estlcam too.