Advice on cutting ebony

[Bob Eustace]

Got to cut 2" letters in customer supplied ebony. (Using the band saw off profile cut method) What would be the best feed and speed for a 1/8 end mill going no deeper than .250 and suggested pass depths. Using a bog standard Buddy with spindle. Never cut the stuff before so all advice muchly appreciated!

[scottp55]

It's a small world Bob, cutting a small monogram type plaque(pocketed letters in Macassar Ebony) for my mothers 82'nd birthday tomorrow. If anybody answers this, can they toss in feeds and speeds for a .5" 90 degree vbit I'm using for a chamfered edge. Bob, was going to play with a piece I've been cutting plugs out of to get the best out of the .125" tomorrow. If no answer, I'll let you know.

[Brady Watson]

Start using the same settings you would for maple. See, hear & smell what is going on. Adjust as needed.

It seems like a poor use of real Ebony...There are cheaper & more sustainable options out there.

-B

[scottp55]

Thanks Brady, 1.1,.05, 14k for starting it is. Mine is going right next to her antique baby grand piano, so ebony it was from some '97 billets. Know it's precious and irreplaceable, but so's my mother, even if she does say"is that all the machine does? Cut?" :)

[Brady Watson]

Try 1,0.5 @ 13k to start. 0.05 is super slow in Z and will show burn marks.

-B

[scottp55]

Thanks for catching the typo Brady! Bob, also had good luck with .125" depth of cut for the 1/8" and added a final pass of .001" and haven't had to run toolpath twice since.

[scottp55]

That was on hard maple and I did have a .5" ramp, may want to start at half diameter on the ebony.

[Max Girouard]

For cutting out ebony fret boards, I use a 3/32 carbide spiral down cut end mill running at 80 IPM with the router at 23,000 with pass depth at 0.030. I had it going 200 IPM, but I was getting chatter on the end grain portions of the board so slowing it down stopped the chatter.

For cutting out the ebony finger rests or pick guards, I use a .25 end mill 200 IPM, with the router at 23,000 with a pass depth of .125.

I don't recall how or why I came up with these numbers. I'm sure they could be optimized some day down the road but for now these feeds and speeds and mills work well.

[scottp55]

Thanks Brady and Max, I'll use these settings to mill off the chatter marks(deep) to get comfortable, Max, stepover on your smaller bit? Was going to use 40%, to much?

[Max Girouard]

I use them as a profile pass just to cut the board out of the blank after I mill the radius onto the surface. I would think that would be OK? On my 0.023 cutter that I use for inlay pockets, the step over is 40%.

[scottp55]

Thanks Max, Don't have any downs except the 1/4" that came with starters. I think I'll use the .0187" fishtails for the first milling pass as I haven't used them yet and want to see the finish. Will stick with my 1/8" straight as it's a known for maple. Need more bits.:)

[Bob Eustace]

Thanks guys - much appreciated! Financially it is great when the customer supplies the materials BUT it is nerve wracking if one is a worry gutze! This bit of ebony cost $200 hence my nerves!

Brady
Its for a mariners compass 48" diameter, going into a beachside retirement cottage. Flooring is Jarrah which in this case cut beautifully. Trying to get the guy to use beech as the other colour. Wont it be wonderful when you can do this stuff on a fully installed floor when the Handibot gets fully developed. Luckily we dont have to install this one!

[scottp55]

Bob, Macassar ebony, not Gabon. Onsrud #61-040 .125" straight, pocket depth .2" 1.0,.5, 14,500. .06" deep .5" ramped passes. DO NOT PUT SCREWS THAT CLOSE TO THE EDGE---SPLITS.

[scottp55]

Oh, Followed someone's advice (Joe?) and profiled outside line at same #'s before pocketing.

[bleeth]

Looks very nice Scott

Doing a light texture on the recessed background takes longer to cut and needs a bit change to a ball nose but will cut your sanding way down.
Another common trick, although not sure I would want to do this with something as dear as ebony, is to cut the letters out of another piece entirely and cut insert pockets for them after you pocket and/or texture the background.

[scottp55]

Thanks Dave, I messed up at the last second. Had to mill .2" off to get rid of a check I hadn't seen in the rough and then my square drive finish screws were too long to use, had to use spax to get length right. Last cut was .25" down spiral and that darn screw head measured .26" from the line. Didn't chance it and drilled another hole closer to the edge on the other corner and split a really nice 2" long strip off the lower left corner. Tons of ways around it and it shouldn't have been issue,but was trying to beat a thunderstorm and didn't want to shut down in the middle. Let's see clean with acetone to remove oils, but what kind of glue did I use 10 yrs ago for ebony? Worst case do it again, and use that for some wedges I need any way, I only lost .2". Darn.

[bleeth]

Pretty sure you can use TB. Used it for years for Teak on boats as long as we used acetone first. Someone on another forum said they have used all 3 types with no problem. They wipe with denatured-a little friendlier than acetone.

[Bob Eustace]

Well machined it on the night shift last night. Used Brady's speeds and feeds and they cut fine. A million thanks guys - the forum at its helpful best, You dont get chips with this stuff and the dust really looks evil! Cutter lifes really only about 100 inches. Just got two 1/8 chips on the end of two circle bits. Bit of luck - the customer is going to do the stars - yahoo! Convinced him to cut the bit we machined on HIS bandsaw! Anyway the guy is so happy he has given us the mating piece of this chunk! I didnt ask how he came by it! Sorry the pic is upside down. Was working fine when IOS7 first came out and I was jumping for joy!

[scottp55]

Thanks Dave, Breathed so much acetone doing kayaks and canoes back in the day a little more won't kill me and that's all I've got left is a little bit. Will try TB3 and if it looks horrendous, will chamf and put in claro or quilted base ( Mother dearest asked where the holes were to hang it up!---No way!). Bob, looks good (nervous making though), what bit and how did the bottom of cut look? Priced Gabon last night $150-200 bf . Glad it went well, Nice tip he gave you. Thanks again Brady and Max.

[Bob Eustace]

Scott the bottoms look good but of course it didnt matter in this case as they were cut off in the bandsaw. Circle segments were cut with 1/4 downcut and the letters 1/8 downcut. No special finish cut - just ran it twice.

[scottp55]

Thanks Bob, Just wanted to know for future reference as I still have 2 1/2 billets left. On mine the only cut that looks like it should have been run twice was an online profile with a 90vbit. That matching piece you've got shouldn't be so nervous making, except this time of course it will be YOURS. I've got to build a jig for the Desktop, screws are driving me batty.:)

[Bob Eustace]

Scott TJ did a tutorial on hold downs on the Desktop. If you email him he will send you the files. Why dont you give the Shopfox clamps in my ebony pic? These work great as long as you dont hit em!!??

[bleeth]

Scott: I think the desktop and that type of cutting is tailor made for cam clamps and stops unless the part fills the whole bed. Even though most of my work on my 4 x 8 is vacuum held, when machining smaller parts that don't get cut out I use that system and it's quick and easy.

[scottp55]

Bob, bought 2 of the shopfox to check them out and like their looks. Problem is the main thing we're doing now is cutting sample board for prototype block face and Dad's taking them around to people who are and people who teach blind tots recognition(yes it has to be taught). protos are 4/4 hardmaple 7.5x24" which leaves just enough room for 4 screws. any jig will be temporary. the actual blocks are 1.75" and there will be 10 rows of 13. Final jig will be Y axis rail with 2 tapered pins bolted on Desktop frame to index 1.5" aluminum frame jig for blocks(130). I was thinking temporarily to make an X rail for first t-slot of 3/4 BB with index pins to add an additional 3/4", and do the same with a Y axis rail in far enough to be stable. It looks to be about 1.5,1.5 from prox's.. For through cutting of thinner material(personal stuff) use a bb spoil as big as I can slide on from Right side with Y maxed out to the rear prox. . THat wouldn't leave me any way to clamp the right side of our blanks. Would 2,3,4? shopfoxes in the t-slot hold a 24" board against the X fence hard enough so I can skip a Y clamp? Yes watched TJ's holdown vid. Sorry long winded. Pic shows room on right side, rabbit designates effective cutting area.

[scottp55]

Dave, that's the kind of thing I'd like to do except fancier,boxes,basically play with it. But this machine is only to get one product up and running on a production basis 7 hrs. North of here(7 miles to Canada) and (what a joke) teach some one to operate it on a step 1-blue bit, step 2 red bit etc. Didn't even know what a Shopbot was until April when I found this forum. I will be getting my own Desktop set up EXACTLY like this one so I can continue new product protos after I take this one up North and get it going. That one will be MY baby and then I can do stuff I want, Like finish off the craftsmen details in the house(when I think of how many hand carved wedges I've made and how easy I could do them on the 'bot). Anyways thanks to the many who have helped us. scott