Small laser cut or 3D printed pieces needed

[mangocrazy]

First things first, apologies if this is not the correct place for this query, mods please move where appropriate if needs be.

Basically I have a requirement for 4 small pieces to be laser cut or 3D printed, each roughly 40mm x 20mm. Laser cutting from 1.2mm aluminium (which I will supply) would probably be best, but I imagine 3D printed parts would also do the job.

I have a pair of Brembo motorcycle calipers that I wish to repurpose and fit to a motorcycle which has thicker than standard discs (over 6mm compared to the more normal 4.5 to 5mm discs), and so need some distance pieces made up to increase disc to caliper clearance. Above is a photo of one half of the caliper in question, with the parts requiring augmentation circled in red. I'm not sure whether 3D printed parts would be suitable (mainly because I have very little knowledge of 3D printing), but I would imagine plastic parts could be dimensionally stable enough. They would need to withstand around 20-25 Nm of clamping force.

If anyone can assist I'd be very grateful and will obviously reimburse anyone who's willing to take this on.

Thanks, Graham.

 

[hotponyshoes]

Reminds me of the old princess 4 pot days making spacers for vented discs..

You can make those by hand especially if you already have the material.

Your big problem will be finding a seal 1.2mm longer than the original one so I'd sort that issue before thinking about the spacers..

 

[Agroshield]

As above, the fluid passage on the left side of your photo will be the bigger challenge.

Why can you not glue some aluminium to the caliper, draw around it with a pen and then file to fit?

Similarly a home-made transfer punch for the holes.

Plastic might be very bad as it could creep (do calipers not become warm under heavy braking?) relieving tension on the bolts holding the two halves together.

Shaving 1mm off the brake pads might achieve the same as the spacers.

 

[mangocrazy]

I've previously done something similar, and one of the guys on here was able to laser cut parts for me. Unfortunately he no longer has that capability. For the deeper o-ring I just used some EPDM sheet of the correct depth and used circular punches to make a deeper o-ring. It's not just a question of shaving 1mm off the pads, there are also projections on the caliper body that have to be taken into account.

Making these by hand will be an absolute last resort. Getting the holes drilled in the correct places, expecially with how close they are to the edge of the material will be problematic. If I can possibly get them laser cut that would be by far the best option.

 

[Agroshield]

Getting the holes drilled in the correct places, expecially with how close they are to the edge of the material will be problematic.

Drill the holes first. You only need to get the spacing correct. Use pins to locate them in the correct place on the caliper and superglue on. Masking tape on the caliper. File until the file scratches the masking tape. Break off superglue. Finish file.

Have you a dxf file of the parts? If so, there are innumerable commercial laser cutters (including fully online Chinese ones e.g. https://www.pcbway.com/rapid-prototyping/Sheet-metal/Laser-Cutting.html) who would do this for you. Upload your file to see what they quote with shipping.

 

[mangocrazy]

I don't have a DXF file of the parts and can't think of an easy way to create an accurate one, as the parts are pretty irregular. I'm also really unsure about getting superglue anywhere near the caliper bodies, but will start off with some transfer punches I have to get the mounting hole spacing correct. The hole that connects the fluid transfer between the sides will be tricky to get right.

I'll give manual fabbing a go, but if anyone on the forum offers to do laser cutting I'll bite their arm off (not literally, obvs...)

 

[hotponyshoes]

I think it would take longer to create the dxf than make the parts.
Obviously if you want loads of them then laser but if it's only a one-off..

Cut the bits of sheet out oversize.
Find a drill bit that's a snug fit in the fluid passage.
Drill that through the alloy in roughly the right place.
Put the shank of the drill bit into the fluid hole. Locate the bit of alloy over it with the hole you just drilled.
Find a couple of drill bits the same size as the bolt holes. Put one through the first bolt hole and tap it lightly using it as a center punch. Remove the plate, drill the first bolt hole. Put it back against the caliper using 2 drill bit shanks to line it up with both the fluid hole and the bolt hole you just drilled.
Use another drill bit to mark the 2nd bolt hole. Remove, drill 2nd bolt hole.
Drill out the fluid hole for whatever seal you are using.
Refit/line it all up again and run a scribe around the outside of the caliper to get the outline.
Flap disc to shape and tidy up with a file.

Right hand side (without fluid) just drill one bolt hole in roughly the right place, align with a drill bit shank, use a 2nd drill bit to mark the 2nd bolt hole center.

Hardest part is not hitting the drill bit to hard to make a mark as you'll get a line rather than a dot.
Practice on scrap first.
If you do wack too hard rotate drill bit anticlockwise 1/4 turn and tap it again.

 

[AlexBrown_1]

Im happy to 3D print parts in PLA on a bambu but PLA is almost certainly unsuitable as a material for a final part and would be better suited to using as a model to help you make by hand or machine. Seems like the difficulty might be in getting accurate dimensions for a CAD model.
Although thinking about it, I could CAD and print several attempts and then when it fits right you can send it to be laser cut.

 

[Pete.]

Don't use plastic printed parts it's too compressible and will allow the caliper to flex giving you a soft lever and out of square clamping on the pads. If you do use aluminium bear in mind that the fluid passage has a counterbored hole each side to allow room for the rubber o ring to seal and it's a square section o-ring not a round section one. You'll need to counter-bore the spacer and buy extra o-ring seals.

Personally I would remove the discs and machine them down to a thickness that fits, or even buy a hanful of sets of brake pads and fly cut them down 0.6mm each side.

 

[hotponyshoes]

You could 3d print a jig for drilling the holes but that involves measuring everything up.

If I was going to measure and draw it out I wouldn't bother to print the jig anyway.
I'd just print the drawing onto adhesive paper and use that to mark the holes with a center punch then belt sand the outline.

But even though I have a set of pin gauges, transfer punches, gauge blocks and a cmm I still think it would be quicker to hand run them.

 

[mangocrazy]

Don't use plastic printed parts it's too compressible and will allow the caliper to flex giving you a soft lever and out of square clamping on the pads. If you do use aluminium bear in mind that the fluid passage has a counterbored hole each side to allow room for the rubber o ring to seal and it's a square section o-ring not a round section one. You'll need to counter-bore the spacer and buy extra o-ring seals.

Personally I would remove the discs and machine them down to a thickness that fits, or even buy a hanful of sets of brake pads and fly cut them down 0.6mm each side.

I've given up on using 3D printed plastic parts for the reasons you give. But the original o-ring is a standard round section job. I'll be using EPDM sheet to make a square section o-ring, as I've done before. There's no way I'm skimming the discs - they're ductile iron and are radially drilled/ventilated and material thickness is a real concern. I've been down the route of skimming pads before and I've no intention of doing it again. You either wind up with inadequate backing material or inadequate pad material.

 

[Kram]

JLCCNC do SLS laser sintering - stainless printing, machining or laser cutting at a good price.

However you still need to measure and model the parts.

 

[mangocrazy]

I guess the easiest approach would be to rough up a couple of rectangles with the bolt holes correctly spaced, bolt the aluminium to the threaded caliper half and scribe round the outline, then attack the edges with an angle grinder and flap disk. Messy and a bit time consuming, but should get a workable piece at the end of it.

 

[hotponyshoes]

I guess the easiest approach would be to rough up a couple of rectangles with the bolt holes correctly spaced, bolt the aluminium to the threaded caliper half and scribe round the outline, then attack the edges with an angle grinder and flap disk. Messy and a bit time consuming, but should get a workable piece at the end of it.

I don't think it would need to be particularly messy. You could cut the outline with shears then file to fit. You'll make more mess with the drill swarf.

The clean way to do it is produce a drawing, email it to the cutters, and receive the parts in the post.

If you can't produce the drawing you could post the caliper to me and I'll measure it up, draw it out, 3d print a couple of test pieces and post it all back to you to check.
You can then email the dxf to the laser cutters. I don't think you'll need to send them the material as they will probably have 1.2mm alloy as a stock item.

/\ That will cost you 1.5hrs of my labour, £1.20 for the 2 test prints and 2 lots of postage.

Or, you can send me the caliper and the alloy and I'll hand make them for 30mins labour plus 2 lots of postage

 

[harveyp6]

Or, you can send me the caliper and the alloy and I'll hand make them for 30mins labour plus 2 lots of postage

That sounds like an offer that can't be refused!

 

[hotponyshoes]

That sounds like an offer that can't be refused!

You don't know what my hourly rate is

 

[harveyp6]

You don't know what my hourly rate is

It will be "reassuringly expensive "

 

[Misterg]

I guess the easiest approach would be to rough up a couple of rectangles with the bolt holes correctly spaced, bolt the aluminium to the threaded caliper half and scribe round the outline, then attack the edges with an angle grinder and flap disk.

A hacksaw and a file - it's really not that difficult.

+1 for concerns about the seal. Ideally you would machine a recess into each side of the spacer and use one of the original O-rings each side.

 

[mangocrazy]

You don't know what my hourly rate is

That was going to be my next question... To be honest, if you're happy with it then option 2 is a no-brainer.

 

[mangocrazy]

+1 for concerns about the seal. Ideally you would machine a recess into each side of the spacer and use one of the original O-rings each side.

That really is over-complicating things. Like I said earlier, I've done the same thing on a different caliper and cut an o-ring out of some EPDM mat of a suitable thickness. There's no recess on the other half of the caliper, the o-ring just buts ip against the aluminium casting.

One other thing - I need to do this for a pair of calipers, so 4 pieces of aluminium in total are required. The calipers are mirror images of each other.