dermel'ing

You can do 10-mil spaces easily with a *broken* carbide PCB drill bit used a a cutter.

Cheers, James

What size PCB bit and do you have to trim the end flat? If not what angle do you need?

Like i said,use broken sewing machine needles.

No trimming needed--mine are all serendipitous, carbide casualties from PCB hole-drilling.(*)

The cutting edge is whatever sharp shard of the ragged broken edge happens to stick out the furthest, so the drill bit's size is non-critical. My collection of handy bits, I see, range from #66, #65, #80, to a broken ~0.065" carbide rasp.

The super-small (e.g. #80) bits break rather close to the shank; I think

0.010-0.040" is probably optimum.

(*) (BTW, the best setup I've ever come across for PCB hole-drilling in the lab with fragile carbide bits is the *old* style Dremel model 210 drill press. It moves the *table* vertically, and leaves the Dremel stationary. The #210's slop lets its table rotate a tad about the drill-hole center (harmlessly), but keeps not in 'x' or 'y'. I've not broken a bit since I switched to it.

The newer model 212 Dremel drill press tilts the Dremel from side-to-side as you move the quill. It's a bit-snapper, no matter how much I've tried to take out the slop.

Model 210 (only works with ancient Dremel tools)

Model 212

)

Cheers, James Arthur

Too soft. Glass-epoxy chews them up instantly.

Cheers, James Arthur

Thank you for the excellent information. Very informative post!

I was unable to find a manual for the 210, but I did find an instruction sheet showing the 210 table:

Hackaday has a number of articles on pcb drilling. The comments often contain more useful information and links to other articles and Youtube videos:

Some of the comments are interesting:

Trollicus says: November 29, 2010 at 5:33 pm

A little rule of thumb when drilling(anything) The velocity of the outside of the bit is proportional to the diameter. In other words the smaller the bit the faster you need to spin it. Obviously different materials and bits require different speeds, but given the same material a smaller bit will need a higher RPM. That is why a dremel, which operates at a very high RPM compared to a hand held drill is preferred to this type of setup. I use a dremel model 220 stand. There are some adjustable brass screws on

rubber band(the kind you find wrapped around the base of broccoli) at the top of the press wrapping the power cord end of the drill to the metal cylinder of the stand this prevents any play that will quickly kill bits. I set the drill for as high of an RMP as I can stand(earplugs are a must) and am still on the FIRST BIT! after 6 months of use.(hundreds of holes)

manufacturing/

I'd be inclined to check Ebay to see what they have in linear slides. For example this one:

8mm x 300mm CNC Linear Rail Shaft Optical Axis Bearing Motion Slide Support Set, US $8.49 + $1.99 shipping

Two of them might make a very rigid mount for the Dremel. If good enough, then four more could make a nice xy table. Some stepper motors and a translation table (as described in several Hackaday articles) could automate the process.

Very interesting. This could give full 3D CAD for under $200.

so use a large

proper linear rails and carriages are much much much better that that junk

ear-Rail-n-Carriage

barely good enough to be a toy

That's it.

The drilling table is supported on a post, that is close-fit into a sleeve built into the base. The table is raised by turning a knob, which rotates a large cam contacting the bottom of the table (visible as a half-moon shape in your photo).

The tight fit of post-in-sleeve eliminates slop in 'x' and 'y', and, since the post is centered under the Dremel, the rotational slop puts no lateral strain on the drill bit above.

so use a large

That's interesting. I tried all manner of shimming without success, but I did not try pre-loading.

Just one slide to move the Dremel in 'z' would be enough for hand-drilling.

If you want CHEAP, here you go...

achine/

Cheers, James Arthur Cheers, James Arthur

On Sunday, July 9, 2017 at 3:48:50 PM UTC-4, Lasse Langwadt Christensen wro te:

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Nice. $17 for 350mm is a deal.

Cheers, James Arthur

Love it! I really like using pipe fixtures for the structure. Cheap, strong, rigid, quick and easy to work with. Easy to replace if you scew up. Comes in different sizes to optimize strength vs weight.

Very nice. Thank you.

I use regular steel drills to make holes in FR4. Carbide drills are good if you want 20K holes per drill, and can spin them at 60K RPM in an air-bearing Excelon drill.

Actually, if I don't feel like trooping downstairs to the machine shop, I just punch holes with my usual dental burr in the Dremel. A little wiggling adjusts the diameter.

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics

I saw those on eBay also. That's ok for x and y, but I wonder how the carriage is fixed to the rail so it doesn't fall off when used in the z direction?

There's a row of circulating balls rolling in a groove on each side of the rail, it is rated for several kN side-to-side/up-down

just don't let the carriage slide of the end of the rail or you will be chasing balls

-Lasse

Silly question: how would you make a complete rectangle using pipe fixtures? I'd like to join the two pipes sticking out the front to increase the rigidity. I don't think you can do that with straights and elbows.

The best I can think of is to screw an aluminum angle across the ends. That would constrain the ends in the x direction but wouldn't do much for tilt.

Any genius who can figure out how to make a complete rectangle with pipe fixtures?

Ha. I figured it out. Easy.

you need to use unions

anyway, unless you objective is tinkering for the sake of tinkering, and ending up with something that has a very disappointing performance just go on ebay and buy a cnc router, those that cost a few $100 are not go ing to be great but they will be better than that hack

60k? I think PCB houses spin bits a lot faster than 60k these days. No need for all that though, a Dremel @ 30k RPM is good enough for a hole or two in the lab.

The carbide dental burrs look fine, but you won't be able to carve details as fine as you can with the broken-drill-trick. Carving with a broken carbide drill is almost like writing with a pencil.

Cheers, James Arthur

On Sunday, July 9, 2017 at 5:44:22 PM UTC-4, Lasse Langwadt Christensen wro te:

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going to be great but they will be better than that hack

Not to mention that the Dremel is remarkably unsuited to any serious machin ing. Fine, maybe, for engraving, but more than that is going to be impractical.

We all start off wanting to use a Dremel, though. :-)

Cheers, James Arthur

Left-hand threads? Unions?