V-Carving chipping issues

[maverickx50]

I’m not having much luck with 30 deg or 60 deg V-bits. Letters like M and Y keep chipping. 90 deg works a lot better tho. Tried several different woods and one, two and three flute v-bits with mostly the same results. Maybe they need to make a down cut spiral flute V-Bit??
Any suggestions?

Maybe my V-Bit settings are way off.
1/2" dia 60 deg 3 flute bit
16,000 RPM
Final Pass stepover .02
Clearance Pass .12
Feed 154"/Min
Plunge rate 30

[scottp55]

Slow down.
Try .7,4,17k for hardwoods for 2F.
They do make a 90 LH (KYocera) but no luck with that}
Drop your feed maybe....good luck down to .12" font height with bloodwood.
check bit temp after,

[knight_toolworks]

depends on the wood too. if you do it in two or three passes it really makes a difference. had to do this softwood at .5ips 18k rpms and I think in 3 passes on .25 max depth of cut but it came out perfect with a 60.

[maverickx50]

Just completed a lot of testing with Oak using a 60 deg V-Bit 3 straight flute bit. Seems that first you need to run as fast as fast can be. (rabbit thing as you older folk will recall). 18,000 rpm I never did see any burning even at 10 IPM but wish I had a way to test bit temperature. (I'll fix that soon) I found that about the max reliable cutting speed was around 30/35 IPM. much past that and I started to see chipping. Way off from my first settings and not even close to what I expected based on Internet info. Maybe faster works OK for 3" to 4" letters but most of mine are from 5/8" to 1-1/4" at most. Guess V-carving will just have to be expected to be a longer process than I anticipated. Esp when I go to a one or two flute cutter and see the times double or triple.

[scottp55]

Fredrick, an awful lot of time can be saved by your safeZ settings also. Quite common here to be running a Z1 of between .1-.2" and then a Z2 of around .02"
Have you read this tutorial?
http://www.precisebits.com/tutorials/calibrating_feeds_n_speeds.htm
Just picked up my first CMT 3F 60 today so I have some testing to do also:)

[maverickx50]

Fredrick, an awful lot of time can be saved by your safeZ settings also. Quite common here to be running a Z1 of between .1-.2" and then a Z2 of around .02"
Have you read this tutorial?
http://www.precisebits.com/tutorials/calibrating_feeds_n_speeds.htm
Just picked up my first CMT 3F 60 today so I have some testing to do also:)

Yes and No. I keep going back to this but haven't absorbed ALL that's in there yet. I am using the Z values you mentioned however. Thanks for your input. There are probably a dozen or more critical need to know items I wish I had known prior to turning the bot on the first time. But I'm learning. books, the internet. friends like you all here and yes the hard way as well.

The first thing I learned. (almost the first), was I needed to invest in over $800 in router bits. I am starting with the cheaper ones like someone suggested. Were into a variety of crafts. As such, we need probably a larger variety of cutter bits that someone just making signs or bird houses etc. Oh well only money. I'm old can't take it with me anyway.

[Burkhardt]

....The first thing I learned. (almost the first), was I needed to invest in over $800 in router bits. .......

Sounds a bit high (of course depends on your projects). When I started with CNC I bought all the bits people were recommending from the top shelf suppliers for a lot of money. Surely good stuff but I ended up using only half of them at best and damaging many of the expensive bits due to inexperience.

Nowadays I use inexpensive (but very sharp) 1/8"dia x 2" OAL carbide endmill and ballend bits wherever I can and usually 1/4" solid V-bits. I don't do large production runs and can live with somewhat limited feed and shallower DOC. I buy them in 10-packs and don't worry about breaking or sharpening. Side benefits are easier work holding, minimal kerf loss, fewer chips and way less noise. The only reason to pick the bigger bits for me is surfacing, large pockets, deep v-carves or other deep cuts.

[maverickx50]

To be honest I also purchased a Leigh D4R-Pro 24" Dovetail Jig. Have about 20 high cost bits for that included in my total investment.

[Burkhardt]

...Just picked up my first CMT 3F 60 today so I have some testing to do also:)...

Scott, if that is their "Laser Point" bit, check the v-slot angle it creates. I have that bit and while it said 60 degrees, the cut slot angle in the material is only 55-56 degrees (as measured with an optical comparator). Makes a nice clean cut, though.

None of my other 60-degree bits does that, not even the cheap eBay bits.

[maverickx50]

Scott, if that is their "Laser Point" bit, check the v-slot angle it creates. I have that bit and while it said 60 degrees, the cut slot angle in the material is only 55-56 degrees (as measured with an optical comparator). Makes a nice clean cut, though.

None of my other 60-degree bits does that, not even the cheap eBay bits.

Exact same bit I'm testing now. See my feed numbers above. Nice cut finish wish it would move faster without chipping. Course Oak is one of the worst for that.

[Keith Larrett]

To be honest I also purchased a Leigh D4R-Pro 24" Dovetail Jig. Have about 20 high cost bits for that included in my total investment.

What size ShopBot do you have? I set up my Leigh jig on the end of my ShopBot and use the JointCam software (http://g-forcecnc.com/jointcam.html) to make dovetails.

[cowboy1296]

I use to do most of my v-carving with a 60 and i liked the idea that i was cutting deep. but i was getting a lot of chipping. I started using a 90, add a tiny bit start depth to the settings and have not had the chipping problem. I dont think that it was the bit but i was cutting too deep. Thats my 2 cents worth.

[maverickx50]

What size ShopBot do you have? I set up my Leigh jig on the end of my ShopBot and use the JointCam software (http://g-forcecnc.com/jointcam.html) to make dovetails.

I have a desktop. I set my Leigh on my workbench. I use a Porter Cable 690 to do my dovetails

[scottp55]

Thanks G. and Fredrick,

It's an 858.501.11 and I'll check it.
Mainly bought it to replace a 2F on button cutouts hoping to improve speed on the bevel edge ones.
scott

[Burkhardt]

...Mainly bought it to replace a 2F on button cutouts hoping to improve speed on the bevel edge ones... Well, in that case a possible angle error should not matter much.

[scottp55]

That's what I was thinking. Only .2" material, but also the only edge we have to sand.
A trace more scrap between the batches of 30-60 buttons won't hurt a bit.
Main thing is a smooth cut at 45 degrees to the grain which is our only rough spot.

[maverickx50]

Thanks G. and Fredrick,

It's an 858.501.11 and I'll check it.
Mainly bought it to replace a 2F on button cutouts hoping to improve speed on the bevel edge ones.
scott

yup same bit # I'm using. Like the 1/2" shank. Feel it's more secure and less likely to spin in the Collete.