Notching tubes on a mill + Digital Angle Finder/Inclinometer suggestion

[false_aesthetic]

I use a pretty cheap $30 inclinometer to notch tubes on the Bridgeport.

Bridgeport is trammed but not 100% level (.2 degrees L to R or .126" over the length of the table if I figured that out correctly)

Sometimes the cuts are spot on. Sometimes they're not.

My procedure:

1. Tube in Paragon block as close to the cut mark as possible (w/out cutting through block)
2. Inclinometer on the vise. Zero it.
3. Inclinometer on the tube. Adjust angle. Push up to the edge of the tubing block to make sure it's square.
4. Tighten vise.
5. Leave inclinometer on tube during cut to make sure it doesn't slip.
6. Make cut.

Unless there's a better way of doing this (if there is, please let me know) I'm wondering if my inclinometer is just working within the margin of error and, if so, what do folks recommend?

Thanks!

[e-RICHIE]

Do this, and then correct to suit using a 10 inch or 12 inch half-round bastard cut file.

[VertigoCycles]

I use a pretty cheap $30 inclinometer to notch tubes on the Bridgeport.

Bridgeport is trammed but not 100% level (.2 degrees L to R or .126" over the length of the table if I figured that out correctly)

Sometimes the cuts are spot on. Sometimes they're not.

My procedure:

1. Tube in Paragon block as close to the cut mark as possible (w/out cutting through block)
2. Inclinometer on the vise. Zero it.
3. Inclinometer on the tube. Adjust angle. Push up to the edge of the tubing block to make sure it's square.
4. Tighten vise.
5. Leave inclinometer on tube during cut to make sure it doesn't slip.
6. Make cut.

Unless there's a better way of doing this (if there is, please let me know) I'm wondering if my inclinometer is just working within the margin of error and, if so, what do folks recommend?

Thanks!

You're TIG welding right? Get one of these: Maintube mitering | and a rotary table. The angle finders aren't super accurate and if your cutting to a drawn line, your tube lengths are going to be within 0.020" at best. Even if your angle finder is dead on, if you cut your TT half a mm too long and your DT half a mm too short, it'll open a gap under the DT/HT

[Eric Estlund]

Many of the fluid filled angle finders have a tolerance of 2 degrees. Not sure what you are using. I've had good luck with the digital Fowler magnetic anfle finder for non critical cuts, but any time you are measuring from a tube surface you are introducing error.

Might be worth getting in the practice of cutting long and correcting (per Richard) then saving for that Sputnik Sean mentions.

[jon_norstog]

Fausto,

If you are using a mill, you can get the best accuracy with a tube cutting fixture attached to a rotary table. The table will be more accurate than the angle finder, but the finder will alert you to mistakes, such as a mistake in your conversion between decimal degrees (CAD sheet) and MOA (rotary table). I use a 60 cm vernier caliper to measure and mark the location of the miter. Like Richard, I cut the tubes slightly longer and finish them with a file.

Good luck!

jn

[false_aesthetic]

Thanks for your help ya'll.

I'll definitely be saving up for a main tube fixture but that's not in the cards at the moment.
Cutting long and "showing who's boss" will be the way to go for now.

[Jamie Medeiros]

You have a Bridgeport, you should make your own. Get a self centering vice from some where like Grizzly tools, a cheap 8" rotary table, adhesive metric rule and some scrap metal. If you want to get fancy use the V blocks from Votaw tools. It is how I made my first one and it was accurate enough to do miters in one cut with filing only to clean up the burrs. Very little actual milling involved, most of it was just drilling holes accurately. I made a nicer one only because that one was so ugly. First 300 Fireflies were mitered on that thing.

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