Jig for cutting segmented pieces on SCMS

[Dr_dewey]

Made this "micro-adjuster" for a DW708, could be adapted for other machines.

used a lamp rod which has fine threads and the brass couplings that come with them were soldered to copper plates that were tapped and screwed to a piece of angle iron. A piece of UHMW plastic is used a backstop.

with a small twist one can incrementally change the length of cut by a few thousands of an inch.

 

[Bill Boehme]

Very clever! A woodturner would have turned a knob to go on the back end of the lamp rod. OK, I know, the cobbler's kids go barefooted.

Bill

 

[Malcolm Tibbetts]

Puzzled

Dr. Dewey,

I've cut thousands of segments using a SCMS, but I have no idea what it is that you are showing and I seriously question the need for such segment length accuracy.

How about a little more info?

 

[Dr_dewey]

More info

I was using just a stop block and the clamp, and with scraps would nudge it back and forth so that my cut was within a few thou of the required length. Frustation set in and having to make half nudges or quarter nudges was disapointing. I thought of using a micrometer head to fine tune the stop block, but the cost was too much so i came up with this alternative. the stop block is now moved with fine adjustments of the screw thread. Wasn't it obvious??

 

[Richard Baker]

The segment length doesn't have to be exactly, or almost exactly the correct calculated length. The segments for any given ring just need to be all the same length.

 

[Dr_dewey]

In some cases you need exact cuts

The jig is not for just making rings (which i agree - a certain latitude is allowed). this jig is for accurate cuts required for detail rings - which i have found is required for such as this example.

http://i35.photobucket.com/albums/d176/Rusty_tools/Geromes_method.jpg

 

[Richard Baker]

Looks interesting. Could you post some additional photos please?

 

[Dr_dewey]

a greek key detail ring

i will show how/why this jig evolved, all because of trying to make a greek key detailed ring.

first i tried a design found on a sewing forum based on a 5 x 6 pattern, so if the wood strip was 1/4" then a block was 5/4 by 6/4 . but the joints required more precision than i could get with nudging a stop block.

then a friend found a pattern based on 5 by 7 but used mitred corners. in the pattern the white bits are identical so 4 pieces are done. then there are 2 other pieces that duplicate. the right side and bottom dark one and then the up-rights adjacent. to make these i had to get to within 5 thou in order for them to mesh together, even so i had to use the DS to fine tune the center piece to get them all to sit nice.

after several hours i had enough blocks to make the ring
http://i35.photobucket.com/albums/d176/Rusty_tools/many_pieces.jpg

so far i figure about 13 hours from cuting the stock to forming the ring.

http://i35.photobucket.com/albums/d176/Rusty_tools/the_ring.jpg

the bowl is now in final finishing with some touch ups on the WB lacquer required.

 

[underdog]

13 hours.....

Holy Moses! How much time do you put into these things? I'm a perfectionist, but I don't think I have this much patience!

Nice work!

 

[Richard Baker]

VERY impressive! Thanks for the additional pictures.

 

[Gary]

Dr_dewey

Please share with us a picture of that bowl !

Gary

 

[Dr_dewey]

i would but it is still in "finishing"

and the wife has run off to NY NY for a 1/2 marathon for race walkers - with the camera.