How to make these objects

[shoeshine]

OK, I need to make a bunch of these in various diameters. All regular ellipses.

3/4" material, 1/2 channel around the perimeter.

any thoughts or strategies? My first thought was to just cut them out on the bot and then get some kind of tooling for the traditional router table to cut the channel. ...but... I cant seem to find any commercialy produced router bits that have the right geometry/bearing.

Not coming up with any easy way to do this with the tooling I have for the bot.

Seems I'm missing something obvious.

Thanks in advance
Chris

[penman]

Sorry I can not remember the name, but Rockler, MLC? probally carry them.
You can buy a set of two, or probally one bit for making wooden toy train tracks that would pobally do what you want. One bit cuts a male end ( a shaft with a ball on the end ) the other bit cuts the female end ( a slot with a round cutout on the end ). They are used for making wooden train track sections and joining the track sections together.

Hope the above is understandable, if not ask and I will endeavour to track the bit no down.

Cheers,
Roger.

[myxpykalix]

Chris check this out:


http://magnate.net/index.cfm?event=showProductGroup&theID=231

http://magnate.net/ (http://magnate.net/index.cfm?event=showProductGroup&theID=231)

[adrianm]

Not sure if the dimensions would marry up but for the table I'd use a Trend bearing guided sunk bead bit or for the bot (if you can get round the holddown issue) a Trend staff joint bead bit.

[bill.young]

I don't know how many a bunch is, but if it's not too many what about cutting them in two halves, using a ballnose bit to cut the quarter-circle cove in each half, and then gluing the two halves together? You could drill some alignment dowel holes partway through each piece to keep them lined up during gluing.

[jerry_stanek]

I would make a jig to sandwich the part standing on end for my router table and use a core bit to cut the edge after I cut the parts on the Shopbot

[John David]

Maybe you could use a indexer or a lathe and then part the piece off to the thickness on a saw?

Good luck

[englert]

Without know the size, it looks to me like a bit for roll top desks would work and could possibly be done on the 'bot after the overall ellipse is cut and kerf space is sufficiant. I'm not sure but I think CMT sells those.

Dennis

[srwtlc]

Here's a bearing guided fluting cutter. http://www.eagleamerica.com/product/v164-1042

For a larger flute, a shaper cutter would work too, but would need to have some guide bearings of the proper size. http://www.eagleamerica.com/product/vp13-2656/clearance

Safety while handling the them would be important. Use some good push blocks.

[navigator7]

OK, I need to make a bunch of these in various diameters. All regular ellipses.
Thanks in advance
Chris

What is the application for the ellipses?
Archery?

Cast in plastic with a four piece mold?
UHMW??

[billp]

Scott's on the right track I think. Eagle, and other companies also offer that geometry as a "canoe building bit" for people doing edge gluing on canoe planks that need to be able to take a round hull shape-
http://www.eagleamerica.com/prod_detail_list/s?keyword=canoe

[ken_rychlik]

Chris

Here is the bit that I would use.

http://www.toolstoday.com/p-4933-ball-end-router-bits.aspx

It can all be done on the bot with one bit change.
You would want to do the ball cutter first so the part would not move, then a straight bit to cut it out.

The elipse would need a lead in and out with the start point on the end of that "tail" to plunge,then enter the elipse and do it's cut, then lead back out before comming up.

Then switch bits to a straight bit and cut it out.

Vcarve will not show the preview with this cutter, but it will work. I use the same type of lead in to cut dovetails, but it won't show in preview either.

If you need help with the file email me.

[shoeshine]

ahh fantastic, thanks for the leads folk.

Clearly I simply didn't know what to call them.
The double bearing fluting bit is exactly what I am looking for.

Appreciate it.
Chris

[erik_f]

Like Ken said this could be done with one bit change on the bot...all you really have to do it get the proper lead in and lead out...I would take the help he is offering and learn something new that might help you on a future project.

[shoeshine]

Yeah I thought about that, but looking at the geometry of the bit that Ken reccomended, I dont think I could get a full depth channel. If I am undestanding it right, I would get maybe 3/8" depth. These have a 1/2" tube that get slotted in the groove and need to seat firmly. But I appreciate the idea.

Chris

[oddcoach]

msc has the tool you need
http://www1.mscdirect.com/CGI/NNSRIT?PMCTLG=00&PMAKA=78066446&partnerURL=http://catalogs.shoplocal.com/mscdirect/index.aspxopagename=shopmainPcircularid=16558Pstor eid=1040626Ppagenumber=540Pmode=

[widgetworks_unlimited]

@Chris - do you really need a round bottom on the slot to support the tube?

I cut parts similar to yours but mine have a square slot in the edge. The bot does this with a T-slot type cutter much better and much faster than a router table/guide bearing setup.

With the square slot, you can vary the width and depth to create a press fit for your tube, which may be helpful.

If it's gotta be round, I'd probably cut blanks out of a sheet and then use a 1/2" ballnose on the 4th axis to add the slot.

[gundog]

If I were making that part in my shop I would cut the outside shape on the bot and use a a bit with a bearing in a manual router table to put the groove in.

I make a round roller from 1.250" UHMW plastic that I make in this fashion except I am using a roundover bit with a bearing coller to round over one side when the part is completed. Just because you can do something on the SB doesn't mean you should. The SB is just one of the tools in my shop and it works best for some things and not on others.

Mike