Drilling holes at an angle in sheet brass

[robrmcc]

Hi all, first time posting. I need to drill a 1" hole at a 30 degree angle in 1/16" sheet brass plates that are 1-1/2" x 2". This will be a flange for Uillean bag pipes. I think the options are end mill, annular cutter, hole saw or step drill. Anyone have any advice? We want to fit a 1" length of 1" O.D. brass tubing into the hole and silver solder it in place. So the hole has to be pretty close but not fantastically accurate.

All advice will be duly considered.

Thanks!!

 

[RobinHood]

The shape of the hole will be elliptical.

The options you listed might work. You’d have to somehow hold the thin plate and machine it at the 30* angle - could be challenging because 1/16” sheet is very flimsy. You would temporarily glue it to some backer board and machine through it that way. Then release the brass sheet after you are done.

You could take the 1” pipe and cut it at the 30* angle. I would then place the cut pipe on your 1/16” brass sheet and solder it on. Then, from the opposite side, drill a hole for file access and, using the inside of the pipe as a guide, carefully file the opening.

You could also use the cut pipe as a guide to mark the elliptical shape onto the piece of brass. Drill a hole, and using a jig saw, cut it out. Solder and finish from the opposite side.

 

[robrmcc]

The shape of the hole will be elliptical.

The options you listed might work. You’d have to somehow hold the thin plate and machine it at the 30* angle - could be challenging because 1/16” sheet is very flimsy. You would temporarily glue it to some backer board and machine through it that way. Then release the brass sheet after you are done.

You could take the 1” pipe and cut it at the 30* angle. I would then place the cut pipe on your 1/16” brass sheet and solder it on. Then, from the opposite side, drill a hole for file access and, using the inside of the pipe as a guide, carefully file the opening.

You could also use the cut pipe as a guide to mark the elliptical shape onto the piece of brass. Drill a hole, and using a jig saw, cut it out. Solder and finish from the opposite side.

We tried the 30 degree cut and it is really awkward to get the pipe in the right place. Also this flange has a press fit hose that goes in it so we want to keep about 1" of contact length for that but reduce the height of the pipe piece. Some of the pipe ends up in the bellows itself. Have attached a picture to give a better idea of what we want to do.

 

[YYCHM]

Why does it have to be 30 deg and not 90 deg with elbow added?

 

[YotaBota]

You could clamp two pieces of 2x4 (wood) together, drill your hole thru at 30 degrees, then insert the brass between the 2x4's, lined up with the hole of course, re-clamp and the drill through. The pre-drilled hole in the wood holds the drill at the correct angle and the brass is clamped firmly between the wood pieces.

 

[Janger]

I like the sandwiching it perhaps though with some plywood. Clamp at angle then use a step drill to make your hole.

 

[PeterT]

Do you anticipate making a batch or single/low part count?
A single could be made with a template & simple hand tools like jeweler saw & dowel/sandpaper finishing to the line. I can print you a 1:1 PDF to attach with adhesive or whatever. I do this all the time making parts. The paper template is removed with bit of alcohol or solvent.

 

[robrmcc]

Thanks for all the answers. First, the right angle idea is out as the 30 degree angle is traditional and more comfortable for the player. We will be doing small runs of ten likely so don't want to have to cut them out one at a time by hand and we want a nice fit to the pipe piece so want a clean hole with clean machined angles. I like the clamp approach but might look at coming up with something a bit more secure than 2x4s. It is a pretty small part so proper tooling to hold the part and guide the drill might be the way to go with the center cut end mill or better yet an annular cutter.

 

[PeterT]

For multiple parts, maybe a drill jig from a block of wood? It starts out rectangular, drill the 1" hole through the top. Then lay on side & cut the 30-deg split line Now you have a top & bottom jig assembly that would (hopefully) guide a hole saw from wandering. The trick is jig alignment & attaching the brass in the parting line. I've shown some alignment pin holes near corners that could be drilled through the brass stock assuming it was oversized so everything is sandwiched & secure during hole saw drilling. But then you would reference off these corner holes to make the finished brass part to reduced/final rectangular dimension. More work. I've had good pretty good luck with temporary adhesive bonding metal on wood jig (in oblique mode), but this one is a bit more challenging with the angle.

The drill type is a pros & cons thing. Hole saw has solid cup OD so safer. But teeth are kind of coarse so it might dig in on the thin metal. I've seen similar coping cuts on bike frame tubing etc. but steel is a stronger material. Annular cutters are more precise but have more aggressive teeth, they prefer quite slow rpm & external edges a bit of hazard. You would have to have the jig held in a table vice for stability & safety me thinks.

Or if finish drilling is problematic, drill it undersize with say 7/8" & finish with files. The block provides a good reference guide & you have an integral way of making the 30-deg coping angle. (Handwork though). Maybe you could put a stack of 5 brass sheets in the jig & do them simultaneously in sandwich batches?

I can think of another way. A CAD pattern of finished part outline sent to a laser or water jet cutter & they whack them out to quite exact precision. They typically charge a setup fee. Prices reduce when parts count is increased - the typical problem for small quantity runs. Or... maybe someone on the forum with a CNC! These option would all be perpendicular cut though so might want to really examine your ubing diameter & solder fit allowance.

 

[robrmcc]

For multiple parts, maybe a drill jig from a block of wood? It starts out rectangular, drill the 1" hole through the top. Then lay on side & cut the 30-deg split line Now you have a top & bottom jig assembly that would (hopefully) guide a hole saw from wandering. The trick is jig alignment & attaching the brass in the parting line. I've shown some alignment pin holes near corners that could be drilled through the brass stock assuming it was oversized so everything is sandwiched & secure during hole saw drilling. But then you would reference off these corner holes to make the finished brass part to reduced/final rectangular dimension. More work. I've had good pretty good luck with temporary adhesive bonding metal on wood jig (in oblique mode), but this one is a bit more challenging with the angle.

The drill type is a pros & cons thing. Hole saw has solid cup OD so safer. But teeth are kind of coarse so it might dig in on the thin metal. I've seen similar coping cuts on bike frame tubing etc. but steel is a stronger material. Annular cutters are more precise but have more aggressive teeth, they prefer quite slow rpm & external edges a bit of hazard. You would have to have the jig held in a table vice for stability & safety me thinks.

Or if finish drilling is problematic, drill it undersize with say 7/8" & finish with files. The block provides a good reference guide & you have an integral way of making the 30-deg coping angle. (Handwork though).

I can think of another way. A CAD pattern of finished part outline sent to a laser or water jet cutter & they whack them out to quite exact precision. They typically charge a setup fee & prices reduce when parts count is high.

I just don't think wood will work on this, not durable or accurate enough but might be able to make a jig out of aluminum or even steel. Don't laser or water jets just do 90 degree cuts on the vertical? I actually want the inside edges of the hole to follow the cutter and be tapered so you get a close fit to the piece of pipe otherwise the silver solder line is too visible if there is a big gap.

 

[PeterT]

I think it might be fussy for water/laser shop to support the stock on an angle. I think the heads have to be consistently positioned relative to material surface, no 2.5D. The ones you see where the head swivels (multi-axis) would be cost prohibitive I would think, but never been down that road.

But I think a CNC mill setup could do this cutting action assuming brass could be reliably attached to angled tooling block kind of like like my grey bottom part. That would yield the perfect angle (coping) cut of the circle/elipse. CNC is not my thing but maybe one of the guys will chime in.

 

[robrmcc]

I think it might be fussy for water/laser shop to support the stock on an angle. I think the heads have to be consistently positioned relative to material surface, no 2.5D. The ones you see where the head swivels (multi-axis) would be cost prohibitive I would think, but never been down that road.

But I think a CNC mill setup could do this cutting action assuming brass could be reliably attached to angled tooling block kind of like like my grey bottom part. That would yield the perfect angle (coping) cut of the circle/elipse. CNC is not my thing but maybe one of the guys will chime in.

CNC setup would be too expensive for runs of 10. Likely even a laser or water jet is too expensive. Why I want to figure it out on my own mill.

 

[Janger]

Hold it at 30 degrees ina small vise. Bolt the vise to a rotary table. Using a longer End mill start at the centre and gradually spin the vise and make the hole from the centre to the edges.

 

[PeterT]

Oh you have a mill! PFFFTTT... Forget all this stuff then. I assumed you were like a walk in customer with a hand drill LOL

Your requirement reminds me of an angle jig I had to make. If you could sandwich all 10 brass sheets together with temporary adhesive, mount to jig, you could drill the 1" hole obliquely with annular cutter, they would all get the same perfect ellipse miter angle. But I cant see how you could entirely complete rectangular profile in same setting because the 2 uphill/downhill edges would also get angled. The width could be properly milled 90-deg on side of end mill though. So a second operation/jig may be required.

There might be a way to mechanically fixture & hold the brass. In terms of adhesive, some things to ponder:
- CA glue is hit & miss for me. It prefers porous material so sometimes you see people use painters tape as inter-bond. I find it needs high heat and prying to let go. CA debonder will not get in the cracks well, most solvents wont do much. I've bent some thin metal parts trying to pry them apart, but they were thinner material.
- House brand cheapo 5-min epoxy has some good attributes. It will likely stand a good chance of bonding and it has more predictable softening/parting under heat from a heat gun, no residue. I can find some pics of a guy who pots his aluminum parts into/onto MDF wood holding fixtures, does all the feature 3D milling, then just heats it up & metal part releases from glue.
- industrial double side tape works quite well & is quick to apply & lay up, but I have yet to solve the riddle of de-bonding. Thinners just turn it into a gooey mess. Heat just softens & then burns... no success yet
- specialty waxes/resin? I see pics of jewelry folks bonding metal with a special relatively high temperature substance? Comes in a stick or blob & they heat it with a light torch or gun? Haven't had my own hands on the stuff though.

 

[whydontu]

Makes PeterT’s jig. Use decent quality steel. Dowel pin the two jig halves and machine a 1/32” recess in the bottom to solidly locate the brass blank. Tight control on the 1” bored hole. Make a nice clean sharp 1” diameter punch, hardened. I usually start with 4140 CrMo bar, easy to machine and hardens reasonably well. Clamp the two jig halves tightly together. Get a BFH to smack the punch. It’s only 1/16“ brass.

Needs maybe 7 tons of punching force.

https://www.trick-tools.com/common/documentation/punching_data.pdf

 

[PeterT]

Another option. If your mill head can rotate 30-deg, plunge drill a brass stack-up using the quill? (drill press mode). This would negate the angled jig. But I think you would still need a second machining op to complete the rectangular profile in regular mill head orientation.

 

[Mcgyver]

its only 1/16....I'd make a hole and file the ellipse. The humble file can solve many problems. To get a really good fit, black magic marker on the pipe, test fit, file the black off the sheet. Kind of like scraping.

Also, on the silver solder, does it have to be SS? I do lots of SS'ing but where I can I use soft solder on brass. Very often it is strong enough and it does not anneal the brass the way SS temperatures will. Also, while 1/16 isn't that thin so maybe not an issue, the higher heat from SS can make a mess of brass sheets from warpage.

Maybe you're way ahead of me and have done 1000 of them, but if this is a first adventure, I've found soft solder can be better for a lot of brass assemblies for those reasons

 

[historicalarms]

being as this isn't a one-off manuf., you state multiples will be made. Personally I would cut your sheet with square shoulder cuts and made oblong to a perfect fit at the angle you desire to the pipe...now build a jig that holds the flat sheet and the pipe at the perfect angle to each other so no movement is allowed then solder. the solder joint will be stronger than if you cut your sheets at the angle you specify.
Once you find the perfect oblong dimensions of your sheet cut-outs making multiples will be a snap with the jig.

 

[Mcgyver]

yeah, the multiple part wasn't in the OP....I wouldn't be up for filling and fitting 10 at a time. I'd be thinking making a fixture that holds them at 30 degrees and bore - as they are not that big, maybe even in the lathe? Its just quicker than stopping and adjusting a bore head mutiple times

 

[Darren]

I'd be looking at making a punch and die fixture