feeds and speeds - 1.25" hard maple lamination

[cdodds]

hi guys,

i'm trying to experiment with cutting some rattle profiles (.75" hard maple with two 1/8" layers glued on top - total thickness roughly 1.25")

i overlooked some important details on the first run, feeds and speeds were waaay off, pass depth was too deep, and i snapped my .25" downcut bit right off.

i'm new to this and would eventually like to use double sided machining to dish out the skinny mid section, but for now, just trying to dial in feeds and speeds for the profile cut.

attaching pics of my results, up until the bit broke, as well as a finished rattle. don't have an indexer, which i'd imagine would make turning a rounder rattle like this easier, but have been playing with roundover bits to achieve something similar for the time being.

if anyone has recommendations on proper feeds and speeds for cutting 1.25" maple, i'm waiting on another .25" downcut and hope to cut again soon, this time with a little more success :)

the rattles are roughly 6" long, and about 1.75" wide at the widest point.

thanks,
chad277702777127772

[cdodds]

also, if there would be a more suitable bit than the downcut, please share your thoughts. thanks!

[bleeth]

What model bot and router/spindle do you have.
Answer is dependent on that.

[cdodds]

yes, that might help :)
desktop max with a spindle

[bleeth]

I would keep my feed around 1.5-2 ips and step down no more than 1/4-3/8"
Spin around 12-14k(adjust according to your ears.)
Could likely be a bit more aggressive but why push it?

[cdodds]

Thanks so much Dave,

I will try your recommendations once I get the new bits and will let you know how it goes. I'm in no hurry to push things, and agree, like Scott mentioned, would much prefer taking a little more time on the table if it saves me the hassle of so much sanding later.

Thanks again for your help. I really appreciate you taking the time.

chad

[bleeth]

You're welcome.
I bet the forum would also appreciate your observations on the Max as you become more familiar with it.
As a new model there hasn't been a lot of feedback here yet.
Been thinking about one myself as well.

[dlcw]

I just cut legs for 10 barstools (20 blanks) from 1.25" rustic hickory. Used a 3/8" two flute upcut spiral. 12K rpm, 4IPM. First passes were climb cuts leaving a 1/32" skin. Next cut thru in one pass using 1" x .5" tabs to hold the legs in place. No bit problems, no screaming bits, good clean cuts.

[bobmoore]

I am with dlcw on bit selection. I seldom use down cut bits on hardwood. They tend to burn maple and cherry for me so I leave them for manufactured wood.

[cdodds]

Bob and Don, thanks for your help. I'll add one of those to the order and let you know how it goes. I know it's a relatively simple question for you experienced guys, but it really is a huge help and means a lot for you all to take the time and give your feedback. Thank you! chad

[Justin G]

I think we would be remiss to send a new guy on his way without mentioning that upcut bits will most certainly evacuate a kerf of chips quite well, and will also depending on your hold down method, want to lift material off the table bed. Sometimes if I'm using universal vacuum and cutting small parts I have definitely thrown pieces across the room. That's borderline an exaggeration but I think you will pick up what I'm putting down. You are probably doing four screws in each corner at this point for hold down and that really works quite well. The reasons I stopped doing that was wear and tear on the spoilbloard and for speed considerations with regard to production.

[Simops]

I tend to use a combination of downcut and upcut bits with hardwoods and ply. Quick shallow profile pass with the downcut followed by the upcut to leave crisp edges top and bottom. If I use an upcut only I always get tear out. I'm sure there probably other more efficient ways to do it but this works best for me at my level of experience. Im in no hurry when cutting hardwoods.

Cheers

[dlcw]

Here's what I use to hold down hardwood and small plywood parts. My vacuum table holds the MDO firmly to the spoilboard. I too use compression bits for plywood. Clean veneer cuts top and bottom.

http://www.talkshopbot.com/forum/attachment.php?attachmentid=27785&stc=1

[Bob Eustace]

Good compression bits that wont break the bank come from Fred at Centurian. Also postage is very realistic and first class service.

[cdodds]

Thanks again everybody :) I took good notes and will report back once I get the bits in the mail next week. Happy Friday! chad