any suggestions on how to do this cut?

[Retire2004]

Accorging to your latest post: the cut is through one plane only(so no binding of the TS blade, yes?) I would do a on a TS with a taper cutting jig to control the angle. Clamp the tube to an "L" shaped jig and pass through using the taper jig. You will be left with a whole cylinder which has a slot through ehich I assume is what you want??? SIMPLES

 

[giantbeat]

Hmm. From the pictures I imagine that you'd need your saw blade fully raised to do that, and without a guard. With a well made sled its doable and probably fairly safe, but... well. Rather you than me, sunshine!

yes that was my thinking fully rasied blade, i work with drum shells so the guard is off most of the time, cutting them down in length (the most common job i do) means spinning the shell on the blade... cant do that with a guard on.... its horrifying i know

If its a one off, I'd go with a rigid tenon saw, or router and a flutting jig type assembly.

Could go down the Dremmel route also, might be easier than other ways.

its not a one off, it need to be repeated x 100 +

i will look into the flutting jig, i dont know that one.

Surely by the time you've made a sled, fastened it down just so... you could have done it with a jigsaw? Even a fretsaw?

possibly, but jigsaws are not overly accurate & accuracy and repetition is vital.

 

[giantbeat]

Accorging to your latest post: the cut is through one plane only(so no binding of the TS blade, yes?) I would do a on a TS with a taper cutting jig to control the angle. Clamp the tube to an "L" shaped jig and pass through using the taper jig. You will be left with a whole cylinder which has a slot through ehich I assume is what you want??? SIMPLES

yes, and thats kind of what i was thinking from the start... but with a U shaped jig, a L will be much simpler

 

[Sachakins]

Flutting/barley twist jig for lathe.
Maybe something like this?



Or maybe this

 

[pe2dave]

possibly, but jigsaws are not overly accurate & accuracy and repetition is vital.

Horrible temptation to 'let us know when you're typing with one hand'.
If accuracy is that important, ask someone to set up
a cnc system for your drums?
10sec per cut, might save you a limb.
You choose the trade offs.

 

[paulrbarnard]

dont think i was clear in my post, mentioning rotating the tube, I'm not wanting to twist the cut round the tube at all.. im wanting to do a single straight line cut without any rotation or movement once that tubes in place, hence thinking a sled with the tube fixed in place... id probably need a V block or concaved radius block that is sacrificial as the cut would have to travel through all of it.

Ah then an angled sled is all you need. I had assumed you needed to keep the cut perpendicular to the cylinder.

 

[giantbeat]

I don't know how you make the plywood tubes but is there an opportunity in that process to make the cut before gluing the laminates ?

unfortunately not the way drums are made, it just wont work... if ever you want to know more about drum shell construction or ply tubes, hit me up, been making them for 17 years

Flutting/barley twist jig for lathe.
Maybe something like this?



Or maybe this

cool thing, but id need a big lathe to do the 26 x 20" tubes. ... the cut does not have to run perpendicular to the outer surface so im trying to avoid twisting the tube.

Ah then an angled sled is all you need. I had assumed you needed to keep the cut perpendicular to the cylinder.

thats what i thought, but wanted a 2nd or 3rd opinion... i feel happy its the way to go.

 

[Inspector]

Sled with clamps on both sides and ends holding the thickness of the cut to keep the drum from closing as it is cut. Might need to have sleds for each diameter drum but that can be determined once you make one.
The other option if you can find such an animal large enough is a pull saw where the part is fixed and the blade pulled through the cut.

Pete

 

[giantbeat]

thanks for the help everyone, 2-3 replies saying the sled is the way given i dont need to the cut to twist round the tube.

 

[giantbeat]

Sled with clamps on both sides and ends holding the thickness of the cut to keep the drum from closing as it is cut. Might need to have sleds for each diameter drum but that can be determined once you make one.
The other option if you can find such an animal large enough is a pull saw where the part is fixed and the blade pulled through the cut.

Pete

yeah id double clamp it anyway, we do when we cut straight down the middle, the funny thing is ply tubes dont ever seem to close on the blade, they have so much tension in how they are formed they open up away from the blade as you run down them, as the cut completes they spring open, so double clamping just keeps things steady and stops things "Boinging"

 

[Ozi]

Very basic question. Does the cut go through both sides of the tube dividing it into two pieces or is it one side only?

 

[giantbeat]

Very basic question. Does the cut go through both sides of the tube dividing it into two pieces or is it one side only?

just one side Ozi..

 

[Ozi]

just one side Ozi..

I think people may have been making the same mistake I was, that you were cutting right through.

I'd go for the table saw and sled method, not too much blade exposed and the reeving knife will be OK. Obviously you will need supporting blocks and I would probably fit two ratchet straps to hold the tube down with a quick turnaround time, just keeping the loose ends secured out of the way.

I hope once patents etc. are secured that you will let us in on the details, sounds fascinating.

Good luck

 

[TheUnicorn]

Thinking out loud, so could be way off, but how about tube held (clamped) in V channel, at desired angle, cut with radial arm saw.

 

[Trextr7monkey]

Thinking out loud, so could be way off, but how about tube held (clamped) in V channel, at desired angle, cut with radial arm saw.

I thought about this as an option but then saw the diameter of the bigger tubes!!

 

[giantbeat]

I think people may have been making the same mistake I was, that you were cutting right through.

I'd go for the table saw and sled method, not too much blade exposed and the reeving knife will be OK. Obviously you will need supporting blocks and I would probably fit two ratchet straps to hold the tube down with a quick turnaround time, just keeping the loose ends secured out of the way.

I hope once patents etc. are secured that you will let us in on the details, sounds fascinating.

Good luck

yeah we are going to do a sled test cut.

will happily detail more once i can, its not that interesting, but i have to scratch build everything in my game... and occasionally i get out of scope of my level of confidence when it comes to certain tasks...

thanks man.
G

 

[baldkev]

Ok, just to be clear, it seems to me that you want to make a single cut, through one wall thickness, not through the whole tube? Therefore, a tablesaw sled is actually a safe way. The blade top is within the tube..... riving knife possible, but no crown guard.


EDIT: I JUST READ PAGE 2!

i still stand by the table saw sled

 

[TheUnicorn]

I thought about this as an option but then saw the diameter of the bigger tubes!!

am wondering with careful alignment whether a cut could be made halfway and then the jig rotated 180, then the cut completed.

 

[Inspector]

I thought about this as an option but then saw the diameter of the bigger tubes!!

It could be done on one of the bigger RAs if the arm was turned around and a new table placed lower than the stock one to get the height. It would require another machine and more floorspace though. A sled or multiple sleds would use the existing saw.

Pete

 

[baldkev]

I would add, others have suggested clamping tubes in place, this is fine as long as the pressure is not too great and is downward as, i believe, that would aid flex away from the blade. Riving knife still essential. The ratchet straps is probably a good call