As usual, I must be doing something wrong

[jerry1939]

I do not do stack cutting, as I am not interested in craft shows or Christmas ornaments.

 

Just did a Word Art with small words superimposed on larger words. Cut with 1/8" BB for the top (good) piece, with a 1/4" "sacrifice board" on the bottom.  On 3 places, the inside of the letter "V" chipped.  Had never mixed sawdust & glue for a repair before.  Did that, but was concerned that the paste might not bond, so I put a tiny spot of glue on, with the paste over that.  FAILURE.  Only ended up with glue showing.  Threw it away.

 

The good news:  The only ply I had for a sacrifice board was 1/4" BB (which I put on the bottom, to support the thin, narrow shapes above.)  Threw away the top board, which was intended to be used, BUT THE "SACRIFICE BOARD ON THE BOTTOM IS PERFECT."

 

From now on, if I ever try this again, I will sandwich "the good" 1/8" between two 1/8" sacrifice boards.

 

Thoughts welcome and appreciated.

 

jerry

 

 

[crupiea]

You have to ask yourself why that piece chipped out.

 

Could be the blade you are using , when it hits that corner, is just not up to the task and taking too much wood out even on a very small scale.

 

Or it could be that that tiny piece was unsupported and the vibration knocked the little piece out.  Speed could cause tis too.  a bit too fast.

 

Could be that the tiny unsupported piece was over the hole where the blade goes, the blade is just a hair bigger then should be used and the on the upstroke, bam, piece gets knocked out.

 

i fixed this problem by going to metal blades.  way more teeth per inch.  Bottom looks terrible but i just sand it down.  I use 2/0 for normal 1/8" bb and for super tight areas 3/0.  A #72 bit as well.

 

Ended that problem for me.

[LarryEA]

I just enjoyed reading about your experience. 

One thought is you are using wood times three for one piece.

Why not make the sacrifice boards are good enough to give them away when finished?

[DWSUDEKUM]

Jerry,

 

There generally is 2 or 3 things that can cause tear out like you are discussing. One you have an aggressive blade installed, or Two your ply that you are using is not solid or Three the piece is vibrating from the cutting.  Personally I would use a zero clearance insert and insure that I had a good sharp blade that for wood that small should not be over a #3 ultra reverse ( flying dutchman ) or a 2/0 spiral if that is what you choose.  The zero clearance insert will give your work the needed support to keep it from flexing and breaking from cutting. Hope this helps.

 

DW

[NC Scroller]

I find cutting a single piece of 1/8" plywood very hard unless there is zero small detail.  As DW suggested a zero clearance and reducing blade sizes will help a lot but your best bet is staking several pieces.

[amazingkevin]

Yes zero tolerance will help a lot  with small pieces being cut.I hope i don't forget this today as that's all i have to cut.

[Scrappile]

And, remember, no matter what you do, you are working with wood and it has it's flaws.  Some chip out may occur even with all the precautions mentioned above.

[crupiea]

I have a pack of those playing cards that casinos discard.  They punch a hole in the middle of them.

 

Clear tape that card over the hole in the table and it makes a big difference.

[NC Scroller]

For my zero clearance inserts I use a piece of aluminum flashing that I attach to the scrollsaw table with double sided tape.

Edited August 14, 2015 by NC Scroller

[jerry1939]

As usual, all you folks are awesome.  Immediately share your wisdom.  It is very much appreciated !!

 

jerry