Idea for My Own Tube Notcher

After modifying the cheap Harbor Freight tube notcher so it (should) work okay for the NAU BAJA SAE team, I had a realization. All you need is a clamp and a spindle. In theory I could use (almost) any half decent swivel base vise with pipe jaws or prismatic jaws, and improvise a spindle.

Yes, Jim, you could certainly CNC it, ...

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When I had a similar problem with the bucket loader, drilling parallel bearing holes 48" apart on a mill with a 24" table, I reduced it to clamping on fixturing that gave the tube effectively a square section with straight parallel sides, an easier shape to mount at the desired angle with standard milling accessories. The tube was square but not perfectly straight. I think I used a row of insert vises to create in effect one long flat reference surface. I used them or vee blocks to saw perpendicular 45's on both ends of the water pipe push handle for the sawmill. I don't remember which because I tried several approaches with the equipment on hand.

If I was to make fixturing for round tubing it would be several pairs of bolt-together vee blocks without vise handles protruding inconveniently from the side. A shallow vee on the backs could center the drill bit or hole saw. Recessed bolt heads would let the work be flipped.

I use a Portalign as a portable sliding spindle, but it’s a woodworking tool whose stiffness may be inadequate for other than perpendicular holes in steel. Perhaps if a mill isn't available a square clamp block fixture mounted on a tilted drill press table would do for fishmouthing tubing?

Although not a help to you but perhaps a hint, my Shopsmith serves pretty well as a horizontal or angled boring machine for wood, between the spindle quill feed and the table elevation screw. Its main advantage as a drill press is the two tube support, so the head and table can't twist out of position. The quill feed and depth stop enable very fine adjustments to the rip fence gap for precise joinery. Most of the panel cabinet doors I made on it would hold together by friction.

If you had a spindle with a shell OD of 1" or less it could mount in a 5C spin index for manual feed.

Remember that weldments are generally pretty brute force rough applications compared to machining. Somebody welding up a roll cage and tube frame chassis isn't chasing thousandths for the main structure usually. Their main measuring tool is probably a tape measure and if they are conscientious they use only one tape measure for the whole job. If they are chasing thousandths they probably have a lot more expensive equipment than you or I, and they are letting a machine do ALL the work.

I alluded to this in my initial write up, but I'm not afraid to spend a few hours extra making something if its going to save me 20/30 minutes every time I set it up and use it.

I approach mold making this was all the time. If I am cutting one cavity I just do whatever gets the job done. If I am cutting 20 cavities I may spend an hour or two optimizing cut strategies and doing code simulations. If I am planning to sell the same mold for years I may spend a whole extra day figuring out how to make it more efficiently after the jobs would be otherwise ready to go on the machine. I might even build or utilize existing fixturing to cut more than one at a time to save time on tool changes.

Remember that weldments are generally pretty brute force rough applications compared to machining. Somebody welding up a roll cage and tube frame chassis isn't chasing thousandths for the main structure usually. Their main measuring tool is probably a tape measure and if they are conscientious they use only one tape measure for the whole job. If they are chasing thousandths they probably have a lot more expensive equipment than you or I, and they are letting a machine do ALL the work. Bob La Londe CNC Molds N Stuff

--------------------------- Having drafted custom industrial equipment for shop fabrication and then assembled it largely with hand tools I'm quite aware of specifying and working to appropriate tolerances a senior engineer or machine shop foreman gave me. They could shear and weld large machine frames from 12ga CRS to within 1/16" or better.

The 48" tubes I mentioned were weldments that needed precisely aligned holes at the ends, to align with the holes in the back of the bucket and the frame on the tractor and pivot freely without binding or bending as the bucket rises and lowers. I rigged up reamers on extension shafts to guide from one bucket or frame hole while finishing the other.

Some parts of my sawmill are brute force, with welding shrinkage jacked out "straight" by eye or hammered to a close fit afterwards but many had to be machined after welding for proper alignment. The tolerance on it and the gantry beam is 3/8" bolts in holes match-drilled 0.375" in steps, and most of them start by hand.

At the other extreme some of my firewood sheds are made from rough logs with joints fitted by chainsaw or hatchet.

I alluded to this in my initial write up, but I'm not afraid to spend a few hours extra making something if its going to save me 20/30 minutes every time I set it up and use it.

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I could use a motorized vertical spindle for light indexed spot drilling and milling on the lathe, as some parts are too large for collet block chucks. Though maybe too fast and feeble for hole sawing adapting a Porter-Cable laminate trimmer to the lathe milling vise attachment looks promising. A lathe milling vise could become your spindle mount and leadscrew feed.

At one time P-C marketed an offset base with the offset spindle driven by a cogged drive belt . That type setup could be used to reduce spindle speed . IIRC those trimmers ran at around 22k RPM , way too fast for most drilling/spotting operations .

It would be enough slow it with a Variac and spot drill the indexed locations with a #3 center drill in the collet for further work on the mill. I bored an index disk to fit on the spindle behind the chuck or collet thread protector.

The South Bend lathe milling attachment can apply forces in directions the carriage wasn't meant for. That became obvious when I made a milling vise attachment in night school for my smaller lathe. It has no carriage hold downs in front and the rear ones are out of sight. The fix would be bolts with two heads.

Getting back to the original idea.

By using a commercial or commercial like welding table as the base:

1. You don't have to make a base plate.
2. You can adjust the distance between the cutting spindle and the tube vise without loosing your angle.
3. The base plate (table) is going to be flatter than the typical bent and welded base plate that comes with many tube notchers.
4. Its an out of the box solution that will produce quality repeatable results without spend half your day cobbling up a makeshift solution.

I've spent way to much of my mental budget thinking about this, and I have solutions for tables with different dog hole sizes and grid pattern spacing. To a limited extent even for tables with erratic grid spacing, but maybe not for tables with radically erratic dog hole sizes. LOL.

Making the spindle fit multiple tables is easier than making the vise do so, but both are possible. You still have the same accuracy (more or less) as the grid itself.

How about a portable version . The spindle is on a pivot with the other leg a pipe clamp . Clamp the device to the pipe/tube , set the angle , and Robert's yer mother's brother .

Getting back to the original idea.

By using a commercial or commercial like welding table as the base:

1. You don't have to make a base plate.
2. You can adjust the distance between the cutting spindle and the tube vise without loosing your angle.
3. The base plate (table) is going to be flatter than the typical bent and welded base plate that comes with many tube notchers.
4. Its an out of the box solution that will produce quality repeatable results without spend half your day cobbling up a makeshift solution.

I've spent way to much of my mental budget thinking about this, and I have solutions for tables with different dog hole sizes and grid pattern spacing. To a limited extent even for tables with erratic grid spacing, but maybe not for tables with radically erratic dog hole sizes. LOL.

Making the spindle fit multiple tables is easier than making the vise do so, but both are possible. You still have the same accuracy (more or less) as the grid itself.

Bob La Londe CNC Molds N Stuff

Harbor Freight already makes that and its terrible. LOL

Damn-It Snag! I just visualized a portable version that would work far better than the Harbor Fright version. It has one of the same problems as the HF notcher. You either have to make part of it telescoping, or make part of it really long with a really long spindle sliding assembly. I made the HF notcher telescoping so you could move the spindle base position. Of course it has another problem solved by using a commercial welding table as the base plate. You have to make a base plate. The base plate is actually more complex (although maybe easier to make accurately) than the bent and welded base plate with the HF notcher.

There is another issue with a portable version that solves all the other problems. It may be too big, heavy, or just awkward for some folks to wield effectively. I guess it could be made out of aluminum... LOL

There is one "kinda" advantage for my idea for a portable one. If deigned properly it could fold up like a drafting compass for storage. Not as compact as the two piece welding table design, but not horrible.

HEY! YOU DID THAT ON PURPOSE DIDN'T YOU! You took me down a rabbit hole away from the original idea on purpose. What the heck was... OH! BRIGHT AND SHINY.

Another advantage to using this on a proper welding table would be the ease of mocking up jigs and supports. Particularly if the center lines were a nice standard size height above the table/base.

Getting back to the original idea.

By using a commercial or commercial like welding table as the base:

1. You don't have to make a base plate.
2. You can adjust the distance between the cutting spindle and the tube vise without loosing your angle.
3. The base plate (table) is going to be flatter than the typical bent and welded base plate that comes with many tube notchers.
4. Its an out of the box solution that will produce quality repeatable results without spend half your day cobbling up a makeshift solution.

I've spent way to much of my mental budget thinking about this, and I have solutions for tables with different dog hole sizes and grid pattern spacing. To a limited extent even for tables with erratic grid spacing, but maybe not for tables with radically erratic dog hole sizes. LOL.

Making the spindle fit multiple tables is easier than making the vise do so, but both are possible. You still have the same accuracy (more or less) as the grid itself.

Bob La Londe CNC Molds N Stuff

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That makes it simple and very adaptable. Optical benches are similar, plates with grids of tapped holes that make positioning easy and precise.

Having neither I'd consider the mill table as the base. Plates below the sides would align to the tee slot or table edges, coarsely adjustable with parallels as spacers.

I have a very old horizontal milling machine whose spindle head advances on dovetails, in effect a horizontal boring machine. Unfortunately it has a lever feed table meant for production runs after setup, and lacks any dial graduations. It cuts steel much faster than my vertical mill and the vise swivels in a cutout in the table so it could cut angled fishmouths as-is.

Grizzly sells a somewhat similar machine that might suggest something you could assemble from parts on hand.

A mill table or other modestly accurate t-slot table would certainly work. You could key the bottom with pins of actual keys and pull parts up against the most accurate t-slot edge. Tool design and tool setup would both likely be easier using a t-slot table.

Another advantage to using this on a proper welding table would be the ease of mocking up jigs and supports. Particularly if the center lines were a nice standard size height above the table/base. Bob La Londe

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I have an improper welding table, a street drain grate that was cracked before installation and discarded. Around here we trade scrap steel and broken tools, which is how I got and fixed the rock drill. I ground the grate top flatter by testing and marking with a straightedge. By some definitions it's portable, though so is an upright piano because it has handles.