I was helping a friend turn a bowl yesterday, and messed up. I turned a mortise on what would be the bottom of the bowl to mount it on when we turned it around to hollow the inside. In a classic "me" move, I turned it too large, about 4.25". I'm having trouble finding G3 jaws to fit this opening. Would a cole chuck be safe? the mortise is only about 1/2" deep. I've also considered turning a jamb chuck and using his spur drive with a live center to hollow the vast majority of the bowl, then use cole jaws to finish the last bit. This bowl is about 15" diameter. Does anyone have any suggestions?
Sawdust2012
I would turn 1/2" off the outside, and cut a new mortise. Also, 1/2" is pretty deep, 1/4" should do it.
Close your chuck jaws, measure the diameter, make your mortise just a wee bit bigger.
Cole jaws are for less than 1000 rpm, light cuts, not for hollowing.
Close your chuck jaws, measure the diameter, make your mortise just a wee bit bigger.
Cole jaws are for less than 1000 rpm, light cuts, not for hollowing.
Cut youself a plug to fit the botched recess, glue it in, and start over, carefully measuring so you don't repeat that mistake again. When done hollowing the bowl, jamb chuck it and remove the repair…... Jerry (in Tucson)
No way would I consider using Cole Jaws. Jerry's approach is the most likely to save your bowl.
I am more a fan of tenons or glue blocks than I am of mortises/recesses in the bottom of a bowl. Even with dovetail jaws and recesses, I have had workpieces turn on the jaws in the event of a catch which either throws the piece off the lathe or spins it enough that it no longer runs true.
In my opinion, you are much safer with either a tenon (which the jaws can really bite down hard on) or a glue block which performs the same function as a tenon. I am sure there are turners that have horror storied about glue blocks, but I have never had one fail. Glue block failures that I have heard about occurred when the glue block being used was either soft wood (Pine, Fir, etc,) or plywood. I make glue blocks with hard maple and use TiteBond I (red label original) that I let cure overnight.
I am more a fan of tenons or glue blocks than I am of mortises/recesses in the bottom of a bowl. Even with dovetail jaws and recesses, I have had workpieces turn on the jaws in the event of a catch which either throws the piece off the lathe or spins it enough that it no longer runs true.
In my opinion, you are much safer with either a tenon (which the jaws can really bite down hard on) or a glue block which performs the same function as a tenon. I am sure there are turners that have horror storied about glue blocks, but I have never had one fail. Glue block failures that I have heard about occurred when the glue block being used was either soft wood (Pine, Fir, etc,) or plywood. I make glue blocks with hard maple and use TiteBond I (red label original) that I let cure overnight.
I think Jerry has the best advice for your problem.
Whether you use a mortise or tenon to mount a bowl blank determined by size of the blank, moisture content, or finial design.
I have never had a failure using paper PVA glue joints, waste blocks and face plates before getting a chuck. I have use a waste block & CA glue in my chuck with no problem, but pretty apprehensive.
Whether you use a mortise or tenon to mount a bowl blank determined by size of the blank, moisture content, or finial design.
I have never had a failure using paper PVA glue joints, waste blocks and face plates before getting a chuck. I have use a waste block & CA glue in my chuck with no problem, but pretty apprehensive.
Hey Dust, if you're gonna be doing a lot of turnings, make yourself a go, no go tool. One size is the minimum that your chuck is ideal for a recess, and the other end of the tool would be the maximum. Anything in between would be perfect. It'll save you time in the long run.
I use one for tenons. . It's nothing more than a 6" long piece of 1/4" plastic with a cut out at each end to these sizes, 1 3/4" and 2 5/16". When cutting tenons, slip it over the tenon. If it doesn't fit on the larger size, keep cutting. If it slips over the smaller size, you done screwed up. It's not supposed to slip over the smaller end.
Recesses would be about the same, but you would make a different type of jig…........... Jerry (in Tucson)
I use one for tenons. . It's nothing more than a 6" long piece of 1/4" plastic with a cut out at each end to these sizes, 1 3/4" and 2 5/16". When cutting tenons, slip it over the tenon. If it doesn't fit on the larger size, keep cutting. If it slips over the smaller size, you done screwed up. It's not supposed to slip over the smaller end.
Recesses would be about the same, but you would make a different type of jig…........... Jerry (in Tucson)
Well, heck, TheDane, that's a mighty fine looking tool. Instead of talking about it, you have a picture, and that's worth a thousand words. .Hey Dust, if you re gonna be doing a lot of turnings, make yourself a go, no go tool.
Here s one I made for my Nova G3:![Image]()
- TheDane
These things like this are like tips people ask about. You've been doing it or using it for so long, you pay no attention to the value until someone jogs the memory by asking…
My tool is a bit bigger and both ends are for tenons. I have never and probably will never use a recess. Jerry (in Tucson)
Attachments
I'm not a fan of recesses/sockets either. I have busted out some pieces by over-expanding the jaws. Tenons, glue blocks and face plates work much better for me.
Gerry,
That is a great little jig and a good idea!!!! Thanks for sharing!!
Sawdust,
Use the glue block….we all have, it's the safest for you and the piece.
Mike
That is a great little jig and a good idea!!!! Thanks for sharing!!
Sawdust,
Use the glue block….we all have, it's the safest for you and the piece.
Mike
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
