Tube End Notching? Should be easy but isn't.

dazz · Jul 8, 2018

Hi
I have a simple problem that should have a simple solution.
I need to notch the end of a 25mm square tube to be welded to a 25mm round tube.
Tolerances are wide. The material is mild steel. I want to use a mill-drill with an MT3 taper.

I tried a 25mm hole saw but it was a failure. The saw did not like the one-sided load and nearly destroyed itself.
I then looked for an annular cutter. I have ER tool holders so I needed a straight shanked tool. I can't get them here. All I can get are Weldon types with so many cutouts in the shank, I don't think they would work with ER collets.

The local price of MT3/Weldon annular adapters is obscene at $USD250.
3MT Adaptor - Annular Cutter - Evolution - Drills Taps and Dies Ltd (DTD)
The exact same item is available from Amazon for 1/5th the price.
Steel-Dragon-Tools-Magnetic-Adapter]Page Not Found but one of the reviews says there is no spring loaded guide rod holder.

Then I found CDCO tools who stock an MT3/Weldon end mill holder for just $18 which does have a draw bar, but it is 1/2", not M12. It also appears that end mill holders are not the same as annular cutter holders.

The most promising option looks like the one here at Amazon

What should be a simple problem has turned out not to be. Is there a better solution?

wheels17 · Jul 8, 2018

Clamp the tube to a sacrificial wooden base. Then use a hole saw pilot drill size drill to drill all the way through the tube and the sacrificial base. Replace the pilot drill on the hole saw with an extended solid rod that passes completely through the tube and into the base before the saw contacts the tube. This has worked well for me. Don't force it.

Edit: If possible, leave enough extra tube so that the pilot drill goes through the tube to stabilize the saw. This also works well for through holes on square tube.

DDoug · Jul 8, 2018

belt sander with a 23-24mm dia roller.

What did you use ? A "Mill drill"..... blasphemer...

Chuck a rubber roller in the spindle, set it to the highest speed, fabricate a little arm with an idler.

Gordon Heaton · Jul 8, 2018

I have no experience with ER collets, but those Weldon shank annular cutters work fine in an R-8. Are you sure they won't work in the ER style?

Glug · Jul 8, 2018

You could mark the outline of the desired shape (trace the tube or print a template), then saw, mill or grind it. Done.

There are some free online programs that will print a template which is then wrapped around round tube. Those can be very handy.

Fabworks · Jul 8, 2018

Hougen's 3mt adapter for their 12000 series annular cutters. Not sure how much this would cost in NZ.

Airgas - HOU1816 - Hougen(R) Rotabroach(R) 2 3/8" X 1 1/2" #3 Morse Taper

Is there any way you can cut the hole in the tube before cutting it to length, so the hole saw engages the tube fully instead of only one side ?

cellardoor7 · Jul 8, 2018

I've notched hundreds of tube ends with endmills. Tube in the vise, cutter beyond full depth, and drive it in with the x. A little of the old in and out with the y if it needs.

Illinoyance · Jul 8, 2018

To bad you are so far away. I have an adapter for annular cutters with a 3/4" round shank with 3 flats. There is no pilot or ejector spring. It has no provision for coolant. If there is a practical way to get it to you I would be happy with $30 US.

I have used annular cutters in R-8 collets with no problem. I don't recall ever trying them in ER collets. The guy who suggested an endmill holder has the right idea.

edwin dirnbeck · Jul 8, 2018

If you have any old lathe,short end mill in spindle square tube in aloris holder works good.Edwin Dirnbeck

MetalCarnage · Jul 8, 2018

I would think that a simple way to do this would be to use either an end mill or improvised "sanding drum", both 25mm, in the drill-mill. Set up a fence to feed the end of the square tube in to the end mill or drum.

-Ron

Guest · Jul 8, 2018

I would use an 8 flute 1" end mill. Did you mention how many? That makes a difference.

grinderguy2 · Jul 8, 2018

Hi,Tim here. Might you try a spiral roughing end mill??? using the correct diameter to obtain whatever radius is needed, plunge in the depth desired. They can be resharpened(changes diameter) but if doing many parts, regrinds can be used to move the majority of metal--save the last nibbles for a new one.

dazz · Jul 8, 2018

wheels17 said:
Clamp the tube to a sacrificial wooden base. Then use a hole saw pilot drill size drill to drill all the way through the tube and the sacrificial base. Replace the pilot drill on the hole saw with an extended solid rod that passes completely through the tube and into the base before the saw contacts the tube. This has worked well for me. Don't force it.

Edit: If possible, leave enough extra tube so that the pilot drill goes through the tube to stabilize the saw. This also works well for through holes on square tube.

The hole saw isn't strong enough to handle uneven cutting forces.
I have tried leaving extra tube but the saw grabs at the bottom of the cut.

dazz · Jul 8, 2018

digger doug said:
belt sander with a 23-24mm dia roller.

What did you use ? A "Mill drill"..... blasphemer...

Chuck a rubber roller in the spindle, set it to the highest speed, fabricate a little arm with an idler.

I am trying to avoid cutting/grinding to a line.
The hole saw is to thin/light to handle the cutting forces. It grabs.

I have a mill but the mill-drill is much better suited to this particular job. It has a quill.

dazz · Jul 8, 2018

Gordon Heaton said:
I have no experience with ER collets, but those Weldon shank annular cutters work fine in an R-8. Are you sure they won't work in the ER style?

I haven't tried an ER collet with the Weldon style annular cutters but ER rely on friction, not grub screws or balls. I don't think the shanks have enough metal surface to support an ER collet reliably.

dazz · Jul 8, 2018

Glug said:
You could mark the outline of the desired shape (trace the tube or print a template), then saw, mill or grind it. Done.

There are some free online programs that will print a template which is then wrapped around round tube. Those can be very handy.

The one in the photo is done with an angle grinder. I have about 50 to do. A grinder would be the option of last resort.

dazz · Jul 8, 2018

Dualkit said:
I would use an 8 flute 1" end mill. Did you mention how many? That makes a difference.

I have about 50 to do this time.
An end mill is the other option. I don't actually need an annular cutter because I aim to take not much off the end of the tube.

dazz · Jul 8, 2018

grinderguy2 said:
Hi,Tim here. Might you try a spiral roughing end mill??? using the correct diameter to obtain whatever radius is needed, plunge in the depth desired. They can be resharpened(changes diameter) but if doing many parts, regrinds can be used to move the majority of metal--save the last nibbles for a new one.

I think a sideways cut will let me distribute the wear up and down the length of the cutter, increasing the cycles between grinds.
The other option might be an insert type cutter.

yroc fab · Jul 8, 2018

I have notched thousands of notches with holes saw in my notchmaster, lathe, and mill and have never had a problem with them cutting on just one side of the saw. I was notching some 2 3/8" hardened drill stem in my notchmaster just today with no problems. I can usually get close to 100 TIG weld ready notches out of A holes saw with no lube on 1.75" .120"wall DOM round tube when we are building roll cages. I run the Milwaukee ICE saws with little problem.

Maybe your set up just isn't rigid enough? How were your hole saws mount? In a mill? What brand hole saw have you been using?

I have no input on your other solutions.

dlane · Jul 8, 2018

I use somthing like this , works good on tube or pipe
Speedway Speedy Notcher Tubing End Notcher

Tube End Notching? Should be easy but isn't.

Stainless

Stainless

Diamond

Titanium

Hot Rolled

Hot Rolled

Cast Iron

Stainless

Hot Rolled

Stainless

Guest

Guest

Plastic

Stainless

Stainless

Stainless

Stainless

Stainless

Stainless

Plastic

Aluminum

Similar threads