Need help with screeching sound

[gmora212 (gerald mora)]

Hello, I’m about a month into using my shapeoko 5 pro. I’ve learned quite a lot reading through the forums but haven’t been able to figure out what my problem is.

I’m making some trays and I’m getting a screeching sound coming off the bit. It happens when the bit runs along the edges of the inside of the tray. Especially worse when it goes into a corner. Currently cutting into soft maple. It also does it when I’m doing the cutout of the trays with a 1/4 down cut bit.

The bit is a whiteside 1404 1/2 ball endmill
Step over .25
Depth per pass .05
Plung rate 12
Feed rate 80
Rpm 10000

Any help will be greatly appreciated. Thank you!

[WillAdams (William Adams (Carbide 3D))]

Are you cutting a slot just as narrow as the tool?

Add geometry and cut as a pocket so as to reduce/relieve tooling engagement.

Where possible avoid slotting and add geometry and cut as a pocket

Making vacuum hose adapters

While cutting up vacuum extension wands for this is expedient, it’s a bit problematic given that Shop Vac recently filed for bankruptcy, was bought at the last minute, and production hasn’t caught up. I need a receptacle for the Sweepy 2.0 dust fitting — one option would be to purchase one from Woodcraft, but Carbide 3D sells blocks of HDPE: which looks to be just barely big enough for things to fit. Measuring the hose fitting I get a diameter of ~63.5mm — offsetting that twice we arrive at…

and/or

Adding geometry to cut as a pocket with a finishing pass

One technique which is often suggested to avoid slotting is to add geometry around a part which one wishes to cut out and cut as a pocket down to tab depth — here’s one technique for that. In this case, the project is a bevel gauge which will be cut out of 0.0625" (~1.5mm) thick aluminum: [bevelgauge] Due to the narrowness of the angles, an 0.03125" endmill has to be used, so after importing and scaling the file (we will be cutting out one which is 3") we select the perimeter and offset it tw…

and consider leaving a roughing clearance and taking a finishing pass.

Best Bit for full cut through

One which has a cutting flute length equal to or greater than the thickness of the stock — pretty much any tool should work. Big thing is the toolpaths — if cutting out, rather than just cutting a slot: [image] Offset to the outside by endmill diameter plus 10% or so: [image] [image] [image] Then cut as a pocket: [image] down to tab height or the penultimate pass: [image] then move the contour down to below the pocket and start cutting at the bottom of the pocket: [image] and…

[gmora212 (gerald mora)]

For the inside of the trays im cutting pockets. I do a rough pass using a .25 stepover to quickly cut out most of the material from the tray. i follow with a finishing pass of .03 stepover to my final depth of the tray.

I’ve read that increasing feed or lowering the rpms can help since the cause may be from the bit rubbing against the material and not cutting. I tried increasing and decreasing the feedrate in CM while cutting but the results remained the same. I have not yet tried reducing the rpms.

[Chaotica (Joel McKenzie)]

I would try increasing your RPM…seems kinda low.