I’ve been thinking about this, but haven’t gone “EUREKA” quite yet. Anyone out there ever tried to cut threads using a bandsaw? Seems like I could tilt the table for the angle of the thread, and pitch the stock for the pitch of the screw?
Any ideas?
Thanks
Replies
The hard part would seem to me to be advancing the stock. How would you do it in a controlled fashion as you rotate the stock so that the spacing between the threads was consistent? Maybe someone has a simple answer for that part of the problem.
Waddaya mean it wont fit through the door?
"How would you do it in a controlled fashion as you rotate the stock so that the spacing between the threads was consistent?"Build a jig (or fixture) to hold the work piece at an angle equal to the lead of the thread. Position a brad along the jig the proper distance to equal the pitch of the thread. As the work advances the piece is turned and the soon-to-be thread actually 'threads' its way along the brad??Just off the top of my head. Nothing else there anyway.
Dave,
Tilt your band saw table, try 15 degrees to start, and clamp the miter gauge, set at 90 degrees, so that a dowel set against the gauge fence will receive a shallow cut from the blade. Now just rotate the dowel against the fence and feed it against the right side of the blade. Once the cut is started it will be self guiding and will create a shallow spiral cut down the length of the dowel. Be sure to keep a firm grip on the dowel since the blade will want to grab and rotate the dowel.
This can also be done, in a similar way, on a table saw with a miter gauge set at the lead angle and clamped to prevent movement. This, and the band saw method, were described in the old Delta manuals from the 1940's. On the table saw you could follow up the initial cut with a molding head to create a spiral "turning".
John W.
hey, just popped in from breaktime and got sidetracked- how exactly would this work on a tablesaw? I've used the cove trick on flat stock pushed through at an angle, but threading a dowel would seem to require more sophisticated handling of the piece, no? If you can sir, pleace elaborate on this process.
Also,
>"On the table saw you could follow up the initial cut with a molding head to create a spiral "turning".<
what's a "molding head" for a tablesaw? It sounds like a shaper bit
Another thing- this thread caught my eye because the other day I was messing around in my shop and attempted a similar -yet decidedly more dangerous - operation. I was trying to give my hammer a more aggressive grip, and thought that this could be acheived by cutting a very shallow groove down the handle in a spiral.
Since I don't have a bandsaw, I was using my chopsaw with the safety sheild disabled, trigger clamped "on" (I know, I know) and the arm retainer holding the blade "closed" as it spun. I had a jig clamped to the back fence which was supposed to hold the piece away and keep the cut shallow. On the opposite side ("outfeed") side of the blade I had a second component which held the "key" mentioned in previous posts, to guide and space the spiral once it got going. Luckily, I decided to use an old hammer for practice (and kids at home-DON'T be like me) and left the head on to hold while I turned. It actually worked pretty good, except for one thing: I had expected he 1/8" "key" to space the groove, and also help limit the depth. Interestingly, once the key entered the kerf it allowed the handle to dive in x amount, then it followed -or lead- the bottom of the kerf which resulted in an increasingly deep groove. Very quickly I was left with a very cool looking yet totally fragile hammer. It looks like one of those flexible wooden snake toys, and even has the same "action". Back to the drawing board. I guess I needed a third element, another block outside the key which would hold the piece out .
Dave,
I would think that maybe adding a screw and nut of the desired thread to the jig and CA glue the dowel to the end of the screw and the nut is fixed at the jig, turning the screw would give you the proper feed.
But what do I know?? LOL!!!
Just my .02
Mike K
Interesting issue, My defalting question is: what to do other than decoration? How will you make a nut or female hole to mate with?
Rick,
The use I've seen for this type of thread is to use it at the end of a shaft, to pull the vee shaped cutter, mounted at the other end of the shaft, thru a hole in making the "nut" for a large wooden threaded vise. The larger (1-1/2"dia or larger) "taps" need several passes to cut the internal threads , and the cutter is advanced with each pass thru the nut-to-be.
What engages the sawkerf, is a piece of sheet metal that's sandwiched in a block with a hole for the shaft. The block is cut thru at the same angle as the pitch of the thread, and the sheetmetal with a semicircle cut out is sandwiched between. The whole affair is clamped securely together, and the shaft turned, pulling the cutter thru the nut. Back out, advance the cutter, repeat. Not unlike the old process used to cutting rifling into the barrel of a muzzleloader.
The male thread for the vise was typically laid out and cut by hand, with saw and chisel.
Regards,
Ray Pine
> How will you make a nut or female hole to mate with?
The right tool for both jobs is a lathe -- the kind formerly used for metalworking. Non numerical control lathes can be picked up at auction for pennies on the dollar, and cut all kinds of big threads. Put a rest on it, get some gouges, and it'll do anything you might want in the wood turning tradition.
-- J.S.
Thread cutting with the band saw is probably possible, but would be at least a two-step process. Cutting the left and right sides of the thread in two setups, and in the end I doubt that the finish of the threads would be satisfactory. The simplest option is to buy the Beall router system from someone like Lee Valley. http://www.leevalley.com/wood/page.aspx?c=2&p=41791&cat=1,43000
Threads can be cut very nicely on the table saw however. You'll need to make a jig, get a special blade made up, or use a molding head with the appropriate blades ground for it, and you will need a wood tap of some kind.
About 17 years ago when my father was living with me, (he is still alive), he was trying unsuccessfully to cut 1 1/2 inch threads with the traditional thread box that I was never able to get to work. I said we should use a router, and he disagreed and said “no the table saw's better because the larger diameter cutter will cut cleaner. I had a profile blade that came from a window factory, that was probably used for cope and stick work. I took it to a saw filer and had him put new carbide tips on, and grind a 60° angle on it. .......Then my father proceeded to play.
The attached photos show what he used to cut the threads with. But since I was at work, my knowledge is secondhand so to speak. If clarification is needed. I can probably call him and see if he remembers.
Photo #1 shows the blade that I had reground, a 4 inch diameter thread, and an off cut from a 1 1/2 inch diameter one.
Photo #2 shows the blade in the table saw. It's about 7 1/4 inch in diameter and 3/8 of an inch thick. I don't remember the cost. But it wasn't all that outrageous, because it was something different, and the saw filer enjoyed doing it.
Photo #3 is of one of the jigs. The two blocks are for different diameter threads of 5/8 and a 3/4. They are at the angle needed to present the proper pitch to the blade. The jig is clamped over the “thread†blade to use, and is rotated 180° to select the other size.
Photo #4 is the bottom of the previous jig. As you can see, little time was wasted making fancy jigs. Only what was necessary to get the job done.
Photo #5 shows a portion of a second jig of 1 inch and 1 ½ inch diameter, with the latter in front of the blade.
Photo #6 is a bottom shot of the jig in photo five.
Photo #7 shows the jig over the blade with the unthreaded side towards the camera, and the threaded part of the jig on the far side. In use, the dowel is started in the near side of the hole and turned against the rotation of the blade. The freshly cut portion of the thread engaging in the far side and drawing the dowel through. The blade is raised or lowered to control the fit of the thread as needed.
Photos #8 & #9 show some of what was used to cut the 4 inch thread. Since I don't have a jig for it, I believe it was done with the miter gauge using the “comb†to control the advance of the thread.
Photo #10 shows the “tap†used to cut the 4 inch threaded hole sitting behind it. It was a section of thread carved out to accept a quarter inch electric in-line grinder, that had a small 60° three wing cutter, positioned at the left end at the start of the thread. Way better than a tap for cutting large threads. If I were going to make one now. I would use one of the imported quarter inch, air powered, long nose die grinders. A simpler shape to carve out and smaller in diameter. Plus the airline fitting would rotate and not tangle as much as an electric cord does when the “tap†is advanced into the wood.
An Acme style thread may be possible, using a saw blade or dado blade in the table saw, and a slotting cutter in the grinder. I can't say for sure because I haven't tried it.
These are my thoughts on the subject, and I hope it helps.
Nice POST! Good information...I have a BEALL but a bit expensive.. SO is my idea... Before I used a old pipe power threader... Set the die 'loose' as possible for the first cut.. Tighten down the die for each succeeding pass..
Thanks for the compliment.I would never have thought of using a pipe threader. Probably because I haven't been around them much. I assume you used the standard dies. Ever consider filing some coarse ones more suitable for wood? You wouldn't need to make them from real hard steel if they're not going to cut lots of material.By the way. Does the Beall cut a decent thread?
By the way. Does the Beall cut a decent thread..Yes.. But like any woodworking tool.. The WOOD is the REAL BOSS!I just used the pipe threader because I had one!.. and the split dies allowed for a gradual cut. By the way.. I did not use the power feed feature.. Just the big old hand wheel!Yes, the thread is a 'BIT' fine for wood but worked for what I wanted.. And I did not experience any 'chipping' of the wood..
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