Cutting 3” Schedule 40/80 PVC pipe lengthwise

[michiganbuck]

I think a table saw would be best for this part.
Another method might to set the 7" long part in a 3-sided box (hardwood), wack in a board (spacer) that would make the part tight in the box, then run it through a table saw cut for cut 1, remove a spacer (or add) to the fence, and run the second cut. Roughly a half minute per part.
The key would be with the table fence set in position for the first cut and using the fence spacer (a board) for the second cut no measuring would be needed...no chance for error.
Yes, need to figure (add) the saw blade thickness (times 2) when making the fence spacer board.

The wack-in the pipe space would be 2" longer at each end of the part( 11"). For fancy, it would be two boards lag screwed together with two springs so as to be spreaders for variable width. of .030 or so. likely the fence spacer would be 1.130" if using a 1/16 wide saw blade.

An exertion table or workbench set close to the saw to keep assemble away from the saw blade.

sandpaper to the inside of the box fixture might be good.

The box could be made the same length as the part, and two C clamps might hold the part in the box at top side, so as not to need the whack-in board spacer.

 

[wood2steel]

Michigan, this is getting pretty funny!
You'd think we were Engineering a critical Strut for the Moon Landing Craft!! Haaaaa--
You've got a couple good table saw ideas there; just got to be a bit careful with the drop cutoff left in the box. Those table saws love to throw loose pieces all over the shop! Know that story; PERSONALLY

 

[latheman78]

Did you try a Dado blade?

 

[metalmagpie]

Do you need a 3" gap after cutting, or before? As you have discovered, the material is not ideal and will not sit still to be perfectly shaped/cut. You can cut out your piece and then heat the pipe and form it back to the correct unwarped OD, or you can cut your part a little wider so it contracts to 3". Your choice.

One way you can cut that is by clamping a straightedge to it and then cut it with a jigsaw with appropriate blade. Since you only have one to do, this should not be burdensome.

metalmagpie

 

[michiganbuck]

a critical Strut for the Moon Landing Craft!! < it is?
No wonder we can't get a Mars rocket off the ground .. They are waiting for this part.

 

[michiganbuck]

QT Op;( just got to be a bit careful with the drop cutoff left in the box.)
The box fixture would have a stop bar (finger) that allows the loose part to travel 1/2" (or what) forward. With experimenting, you may find that you wish to cant the loose section to one side, to the right or left side. If so the stop finger might have a raised button and would be set off angle so to cant to the chosen way.
Too bad I'm so far away, I could make it up a couple of hours.

Note; the box would have side clearance of perhaps .015 so as to not be pinching on the uncut part onto the saw blade. (This depends on the part size width specifications.) The C clamps at the top side would tend to suggest a widening of the part (.005 to .015 perhaps)so would reduce/eliminate the part closing on the saw blade due to internal stresses. The fixture box would be screwed together so if a run of pipe came in oversized diameter the screws would be removed and a shim placed in or taken out.

This is not my line of work (being now retired), but would you consider outsourcing the job?
If my jug/fixture works, I could run it and ship it to your customer.
Very likely I could run it on my table or radial arm saw or put a saw blade on my #2 Cincinnati Tc grinder or B&S 13 grinder.

I do have cutting plastic parts experience with making parts for our deer blind company. Slayer Outdoor Products. Check out our Deer Blinds. They are likely the best in the country.

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[Scottl]

Since you are using a table saw I'd suggest building a "sled" with 1.75" diameter cradles and incorporate a splitter in front of the pipe.

Use semicircular clamp pads (or even rods) on the sides of the ID to keep the pipe from pinching. Make one side an actual clamp and the other spring loaded so it pulls the cut pipe away from the blade.

Flip the piece end to end for the second cut so the side that will remain is the one rigidly clamped.

 

[Doug H]

The task described lends itself to many practical solutions, and a lot of good ones have already been proposed.

Another would be to cut some round wooden plugs to the ID of the pipe, and slip them inside so the pipe holds it’s shape. Cut with your tool of Choice. Tap tue plugs out when you are finished with your cuts. If the pipe has a lot of spring to overcome, I would probably place one every couple of feet. Sawn on a table saw, that should leave a very straight cut with a minimum of dressing to clean up. Set the depth of your blade to the wall thickness of the pipe, plus about an eighth to a quarter inch. You could re-use the plugs to make as many as you wanted.

 

[DanBrub]

I think a table saw would be best for this part.
Another method might to set the 7" long part in a 3-sided box (hardwood), wack in a board (spacer) that would make the part tight in the box, then run it through a table saw cut for cut 1, remove a spacer (or add) to the fence, and run the second cut. Roughly a half minute per part.
The key would be with the table fence set in position for the first cut and using the fence spacer (a board) for the second cut no measuring would be needed...no chance for error.
Yes, need to figure (add) the saw blade thickness (times 2) when making the fence spacer board.

The wack-in the pipe space would be 2" longer at each end of the part( 11"). For fancy, it would be two boards lag screwed together with two springs so as to be spreaders for variable width. of .030 or so. likely the fence spacer would be 1.130" if using a 1/16 wide saw blade.

An exertion table or workbench set close to the saw to keep assemble away from the saw blade.

sandpaper to the inside of the box fixture might be good.

The box could be made the same length as the part, and two C clamps might hold the part in the box at top side, so as not to need the whack-in board spacer.

You put a lot of thought and detail into your suggestion…thx

 

[DanBrub]

Michigan, this is getting pretty funny!
You'd think we were Engineering a critical Strut for the Moon Landing Craft!! Haaaaa--
You've got a couple good table saw ideas there; just got to be a bit careful with the drop cutoff left in the box. Those table saws love to throw loose pieces all over the shop! Know that story; PERSONALLY

Yep…me too. Been lucky so far but have dings in the shop wall as evidence of the risk!

 

[DanBrub]

Got so many excellent responses that it may be more difficult to pick the best one than the original problem I posted!

 

[mike44]

I meant to say the pipes were 10’ long, not 10” … sorry for the confusion, although the final product will be 7” long as seen in the pic. I have been slitting 10-ft long pipe sections and then miter sawing them into the 7” lengths. Based on inputs I’m wondering if cutting them into 7” lengths first and then removing the 1.75” section would be easier

If you have a table saw then first cut the pipe to 7" lengths. Then

Hope this the the correct forum! I have an application where I need to remove a 1.75” wide section of 10” long pvc pipe. (See pic). I have tried building a fence and running the pipe through a table saw but as the saw cuts a few inches in length the pipe tries to contract and pinches the blade. A successful first pass is possible but then the pipe is rotated the required arc length and the second cut started. Since the pipe diameter is already trying to contract the blade pinching issue is worse!

View attachment 374342View attachment 374343

Cut the pipes to 7". Bore a 3" or whatever the OD is 1" deep into a 2x6. The hole will be at the bottom of the 2x6 . Bore holes on each end for 5-1/2" bolts. Split the 2x6 on the centerline of the hole. Install a TEE NUT at each end for the bolts.
Add a 12" piece of 2x6 to the right side , this will ride along the fence.
Place pipe into the hole, snug bolts. This will keep the pipe from rotating.
Raise the blade about 1/2". Set the fence to the left cut with a 1-3/4" piece of scrap lumber. When you make the first cut, then remove the lumber and make the second cut.