Big wooden Threads
-
- Posts: 29
- Joined: Sun Mar 08, 2015 3:03 am
- Model of CNC Machine: Conquest 250, ShopSabre 4896 ATC
- Location: North Bay, Ontario
Big wooden Threads
I drew a 4" diameter threaded section in Rhino and am cutting it on my 4th axis.
It's going to be a coffee table leg threaded into a big nut which is mounted to a burl slab.
I had machined some grooves in the aluminum mounting plates of my indexer so they would locate into the clamping rails.
I cut a spline / tenon to fit into the rails and machined groove.
I had dis-assembled the indexer for machining. After re-assembly it would rotate by hand but not by G-code command???
After an hour of bewilderment I just tried dry running my program and everything worked, go figure!
I made a Z-zero error on my initial run by having it .25" too low. I zero'd of the top of the indexer and added half the tool diameter to my offset for some reason!!??
I realized on a roughing program it travels over parts already cut which can really rack up the machining time!
My solution was to draw geometry for 3 zones, and ran different programs for each. Only the end zones had the deeper passes.
It's going to be a coffee table leg threaded into a big nut which is mounted to a burl slab.
I had machined some grooves in the aluminum mounting plates of my indexer so they would locate into the clamping rails.
I cut a spline / tenon to fit into the rails and machined groove.
I had dis-assembled the indexer for machining. After re-assembly it would rotate by hand but not by G-code command???
After an hour of bewilderment I just tried dry running my program and everything worked, go figure!
I made a Z-zero error on my initial run by having it .25" too low. I zero'd of the top of the indexer and added half the tool diameter to my offset for some reason!!??
I realized on a roughing program it travels over parts already cut which can really rack up the machining time!
My solution was to draw geometry for 3 zones, and ran different programs for each. Only the end zones had the deeper passes.
-
- Posts: 29
- Joined: Sun Mar 08, 2015 3:03 am
- Model of CNC Machine: Conquest 250, ShopSabre 4896 ATC
- Location: North Bay, Ontario
-
- Posts: 29
- Joined: Sun Mar 08, 2015 3:03 am
- Model of CNC Machine: Conquest 250, ShopSabre 4896 ATC
- Location: North Bay, Ontario
Re: Big wooden Threads
One the tailstock end there is an outer ring which just slides off. It's just used for locating.
I have a plywood disc on the indexer end as well with a 1.5" sq block glued to it.
I beveled the corners of on the table saw and used a power planer for my " roughing pass".
I'm running a tapered ball .125" for the finish pass at 70 ipm and 10% step-over.
The first piece I tried 6% and the finish was amazing but crazy long run time.
I have a plywood disc on the indexer end as well with a 1.5" sq block glued to it.
I beveled the corners of on the table saw and used a power planer for my " roughing pass".
I'm running a tapered ball .125" for the finish pass at 70 ipm and 10% step-over.
The first piece I tried 6% and the finish was amazing but crazy long run time.
-
- Posts: 29
- Joined: Sun Mar 08, 2015 3:03 am
- Model of CNC Machine: Conquest 250, ShopSabre 4896 ATC
- Location: North Bay, Ontario
Re: Big wooden Threads
317 minutes later...tadaaah! That was for the threaded section with the taper bit. Bottom hex area was programmed with a .5" ball end with 7% stepover.
-
- Posts: 29
- Joined: Sun Mar 08, 2015 3:03 am
- Model of CNC Machine: Conquest 250, ShopSabre 4896 ATC
- Location: North Bay, Ontario
Re: Big wooden Threads
Next I'll take a crack at the nut. My plan is to machine it from 3 pieces and bond it together.
-
- Vectric Craftsman
- Posts: 289
- Joined: Mon Dec 01, 2014 3:53 pm
- Model of CNC Machine: Homemade
Big wooden Threads
thanks for your post.
- TReischl
- Vectric Wizard
- Posts: 4657
- Joined: Thu Jan 18, 2007 6:04 pm
- Model of CNC Machine: 8020 48X36X7 RP 2022 UCCNC Screenset
- Location: Leland NC
Re: Big wooden Threads
Thanks for all that info!
Hmmm, here is something that might help you if you are going to do a lot of threads like that:
Manual programming! OMG!!!! No, seriously....
You could save a ton of time by doing the roughing with some simple lines of g code.
Here is an example:
Assume the left end by the indexer is X0 and the diameter of the thread is 2 inches and you want 8 threads per inch over a distance of 10 inches. (this is wrapping Y)
G0Z1.5 (make sure tool is above workpiece)
G0X10.25A0 (move to X value and rotate indexer to 0)
G1Z.875F35 (feed to take a cut .125 deep)
G1X0A2880F150 (do the rough cut)
G0ZZ1.5 (retract)
G0X10.25A0 (position for next roughing cut)
All of this is pretty straight forward until you get to the line with the A2880 in it.
The 2880 is obtained by knowing that you are cutting 8 threads per inch and you are doing it for 10 inches. So you have 80 turns. There are 360 degrees in one turn, so 80 X 360 = 2880.
I have made quite a few screws for guys in the woodworking clamp to build wooden vises. I learned very quickly to stick with 60 degree threads for a bunch of reasons. Most importantly is that finding a cutter to use in making the nut is tricky enough without using some obscure shape. I have 2 inch, 8 TPI on my workbench that have been used for about 20 years now with no chipout. Had an antique bench that was all beat to hades and the only really good parts were the nuts and screws.
Hmmm, here is something that might help you if you are going to do a lot of threads like that:
Manual programming! OMG!!!! No, seriously....
You could save a ton of time by doing the roughing with some simple lines of g code.
Here is an example:
Assume the left end by the indexer is X0 and the diameter of the thread is 2 inches and you want 8 threads per inch over a distance of 10 inches. (this is wrapping Y)
G0Z1.5 (make sure tool is above workpiece)
G0X10.25A0 (move to X value and rotate indexer to 0)
G1Z.875F35 (feed to take a cut .125 deep)
G1X0A2880F150 (do the rough cut)
G0ZZ1.5 (retract)
G0X10.25A0 (position for next roughing cut)
All of this is pretty straight forward until you get to the line with the A2880 in it.
The 2880 is obtained by knowing that you are cutting 8 threads per inch and you are doing it for 10 inches. So you have 80 turns. There are 360 degrees in one turn, so 80 X 360 = 2880.
I have made quite a few screws for guys in the woodworking clamp to build wooden vises. I learned very quickly to stick with 60 degree threads for a bunch of reasons. Most importantly is that finding a cutter to use in making the nut is tricky enough without using some obscure shape. I have 2 inch, 8 TPI on my workbench that have been used for about 20 years now with no chipout. Had an antique bench that was all beat to hades and the only really good parts were the nuts and screws.
"If you see a good fight, get in it." Dr. Vernon Johns
-
- Posts: 29
- Joined: Sun Mar 08, 2015 3:03 am
- Model of CNC Machine: Conquest 250, ShopSabre 4896 ATC
- Location: North Bay, Ontario
Re: Big wooden Threads
I finally managed to spend some time cutting the nuts. I cut the first set and it was obvious something was not fitting correctly.
Well, turns out my threaded rod section was cut mirrored with the threads reversed compared to the CAD drawing.
I had modified the post P to correct a lettering test which initially cut backwards. Will have to sort that out!
I mirrored the nut parts so that the " backwards" leg could still be used.
Again i thought I had an error somewhere as the threads weren't meshing fully.
Turns out that there was some untrimmed wood on the edges of the threads at the surface of the bolt.
I trimmed that clear and it solved it.
I just taped them together and it turns like a charm!
Well, turns out my threaded rod section was cut mirrored with the threads reversed compared to the CAD drawing.
I had modified the post P to correct a lettering test which initially cut backwards. Will have to sort that out!
I mirrored the nut parts so that the " backwards" leg could still be used.
Again i thought I had an error somewhere as the threads weren't meshing fully.
Turns out that there was some untrimmed wood on the edges of the threads at the surface of the bolt.
I trimmed that clear and it solved it.
I just taped them together and it turns like a charm!
- highpockets
- Vectric Wizard
- Posts: 3667
- Joined: Tue Jan 06, 2015 4:04 pm
- Model of CNC Machine: PDJ Pilot Pro
- dwilli9013
- Vectric Wizard
- Posts: 1237
- Joined: Mon Sep 30, 2013 12:45 am
- Model of CNC Machine: 3 axis Self Designed Self Built
- Location: Machesney Park Illinois
Re: Big wooden Threads
Wow. Quite the accomplishment. What are these to be used in?
D-Dub
Dwayne
Dwilli
Dwayne
Dwilli
- TReischl
- Vectric Wizard
- Posts: 4657
- Joined: Thu Jan 18, 2007 6:04 pm
- Model of CNC Machine: 8020 48X36X7 RP 2022 UCCNC Screenset
- Location: Leland NC
Re: Big wooden Threads
Nicely done! Impressive!
I particularly like the way you fixtured the parts for cutting. Very creative.
Now you got me thinking!
I particularly like the way you fixtured the parts for cutting. Very creative.
Now you got me thinking!
"If you see a good fight, get in it." Dr. Vernon Johns
Re: Big wooden Threads
I want to make a threaded dowel extension as part of a new leg for an old table.
The dowel is approximately 4 1/2" long and 1 1/2" in diameter.
I'm assembling an Axiom Pro 8 machine, without a rotary accessory. For making these new legs, I may need a different machine.
The dowel is approximately 4 1/2" long and 1 1/2" in diameter.
I'm assembling an Axiom Pro 8 machine, without a rotary accessory. For making these new legs, I may need a different machine.
- scubanimal
- Vectric Craftsman
- Posts: 152
- Joined: Tue Mar 12, 2013 9:16 pm
- Model of CNC Machine: Stinger1 24, Shark HD2 Pro, Aspire,
- Location: San Diego
Re: Big wooden Threads
FYI, Axiom will have a 4th axis upgrade in about 2 months, per what I was told. I couldn't wait so am not getting an axiom, but your situation may be different.
V/R,
Ian
V/R,
Ian