Patternmaking Spade/Paddle Bits
Posted: Sat Sep 30, 2023 2:01 pm
Well, I think Ive got most of the patternmaking stuff figured out, but I know where my weaknesses still lie, which are tapered holes for the patterns, ball shapes, and wooden balls (like you would use for ball cranks). Well, Ive been playing with ideas on all of those and ball shapes, the small ones, I could use with ball endmills, but fitting them in a drill is easier said than done when it comes to larger sizes, lol. Also most of my ball endmills are reground and undersize, so not good for accurate sizing.
Up till now, for the tapered holes, where you would want a hollow cast into a part without making a seperate core/core print, I would cut it out with a jigsaw and try to cut draft into it with my chisels/whittling knife, which always looks pretty bad. Recently I got a spindle sander, which works for larger bores, but anything below 2", it can get interesting to cut it out and sand it, so I was playing with the idea of making some tapered drill bits that would drill through the pattern, and leave a tapered bore, all in one step, lol. Ive made homemade spade bits before and they're pretty easy to make, so I figured I'd go with that style. This is what came out of the idea. These bits are all made from coil spring for the shanks so the drill chuck doesnt tear it up, and spade parts are made from bed frame as usual, lol. They were all stuck in the forge to heat to red hot and left to cool slowly in the forge to stress relieve them and make the weld joint much much stronger/less brittle, and so I could machine them on the lathe to size/shape.
They do have radiused corners on them too, so as it drills down in, it creates a hole with fillet already added in. The sizes overlap a little bit, but it goes from 2" to 1 1/2" at largest, all the way down to 1 1/2" to 1" for the normal wide ones, then the sharper angle one goes from 1" to 1/2" round, which should be easy to pull from the sand. They usually go in 1/2" size increments, but I have a center spot where I want the hole to start on the pattern, and have the circle drawn out with a compass like I usually do on patterns, but I just drill down till I meet the circle layout line, and the hole is done.
The ball socket shapes, Ive been looking at the ones pipemakers use, like the tobacco pipes, since they use a U shape in the pipe bowls, they use a custom ground spade bit like this. There is 3/4", 5/8", and 1/2" ones, which larger ones, I can easily make them when the need arises.
I had a pattern that I needed to make a while back and it had those sizes, which was for a brass block for a glass blower/lampworker that was going to be used after cleaning up to make marbles with, hence those sizes. Ive had a few other patterns that needed half round divots in them of those sizes too. Back then, the one, I didnt know how to do those shapes, so had to 3d print them, which they turned out like crap, and the other ones, I just carved in with my small carving chisels, but those spade bits will be much faster and result in alot cleaner and round holes/divots.
As for the balls, Ive thought about it and Ive seen some people making bits to make beads with using old spade bits, so Ill probably make a few of those in the sizes of 1/2", 5/8", 3/4", and 1", which is common sizes used to make ball cranks and such. Ive looked into just buying beads, but every local place here doesnt have perfectly round ones, and if you can find some, even online, they're all in metric sizes and usually undersize, so I figured that instead of fighting with them, I'd just make the beads myself, lol. I would have rather had actual balls, but I can always plug the holes up with some wax or something since it wont be seen after it's cast anyhow, lol. I have the blanks cut out and everything, just need to cut the profile and shape them, then all of the spade bits will be taken out and heat treated all at once.
As you can see, the spade bits, because they're technically a slow cutting style, they leave a very nice surface finish, which even in soft pine like I was doing there, it was leaving a nice surface finish that needs very little work to finish it up and could easily be hit with some 240 grit sandpaper to get rid of the fuzziness and it'll be ready for finish. (after filling in the spur point/divot with some wax) I tested all of those bits so far using a cordless drill, but I can pretty much guarantee that they'll perform much better and leave a much smoother finish by using the drill press, and for the ball socket spade bits, they'll come out nice and round in the drill press too.
Up till now, for the tapered holes, where you would want a hollow cast into a part without making a seperate core/core print, I would cut it out with a jigsaw and try to cut draft into it with my chisels/whittling knife, which always looks pretty bad. Recently I got a spindle sander, which works for larger bores, but anything below 2", it can get interesting to cut it out and sand it, so I was playing with the idea of making some tapered drill bits that would drill through the pattern, and leave a tapered bore, all in one step, lol. Ive made homemade spade bits before and they're pretty easy to make, so I figured I'd go with that style. This is what came out of the idea. These bits are all made from coil spring for the shanks so the drill chuck doesnt tear it up, and spade parts are made from bed frame as usual, lol. They were all stuck in the forge to heat to red hot and left to cool slowly in the forge to stress relieve them and make the weld joint much much stronger/less brittle, and so I could machine them on the lathe to size/shape.
They do have radiused corners on them too, so as it drills down in, it creates a hole with fillet already added in. The sizes overlap a little bit, but it goes from 2" to 1 1/2" at largest, all the way down to 1 1/2" to 1" for the normal wide ones, then the sharper angle one goes from 1" to 1/2" round, which should be easy to pull from the sand. They usually go in 1/2" size increments, but I have a center spot where I want the hole to start on the pattern, and have the circle drawn out with a compass like I usually do on patterns, but I just drill down till I meet the circle layout line, and the hole is done.
The ball socket shapes, Ive been looking at the ones pipemakers use, like the tobacco pipes, since they use a U shape in the pipe bowls, they use a custom ground spade bit like this. There is 3/4", 5/8", and 1/2" ones, which larger ones, I can easily make them when the need arises.
I had a pattern that I needed to make a while back and it had those sizes, which was for a brass block for a glass blower/lampworker that was going to be used after cleaning up to make marbles with, hence those sizes. Ive had a few other patterns that needed half round divots in them of those sizes too. Back then, the one, I didnt know how to do those shapes, so had to 3d print them, which they turned out like crap, and the other ones, I just carved in with my small carving chisels, but those spade bits will be much faster and result in alot cleaner and round holes/divots.
As for the balls, Ive thought about it and Ive seen some people making bits to make beads with using old spade bits, so Ill probably make a few of those in the sizes of 1/2", 5/8", 3/4", and 1", which is common sizes used to make ball cranks and such. Ive looked into just buying beads, but every local place here doesnt have perfectly round ones, and if you can find some, even online, they're all in metric sizes and usually undersize, so I figured that instead of fighting with them, I'd just make the beads myself, lol. I would have rather had actual balls, but I can always plug the holes up with some wax or something since it wont be seen after it's cast anyhow, lol. I have the blanks cut out and everything, just need to cut the profile and shape them, then all of the spade bits will be taken out and heat treated all at once.
As you can see, the spade bits, because they're technically a slow cutting style, they leave a very nice surface finish, which even in soft pine like I was doing there, it was leaving a nice surface finish that needs very little work to finish it up and could easily be hit with some 240 grit sandpaper to get rid of the fuzziness and it'll be ready for finish. (after filling in the spur point/divot with some wax) I tested all of those bits so far using a cordless drill, but I can pretty much guarantee that they'll perform much better and leave a much smoother finish by using the drill press, and for the ball socket spade bits, they'll come out nice and round in the drill press too.