dermel'ing

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Here's a UMC-to-SMB adapter, hand carved with a Dremel. I'm planning
on doing a fairly complex proto with several UMC connectors, so I did
this for practice. That connector is 0.1" square.

https://www.dropbox.com/s/9v8cu9n1qzjdlq1/UMC_SMB_1.JPG?raw=1

It looms like my design rules are about 20 mil traces/spaces, 1 oz FR4
with a carbide dental burr. I might do a bit better with 1/2 oz and a
smaller cutter.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: dermel'ing
On Friday, July 7, 2017 at 10:08:13 PM UTC-4, John Larkin wrote:
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You can do 10-mil spaces easily with a *broken* carbide PCB drill bit
used a a cutter.

Cheers,
James

Re: dermel'ing
snipped-for-privacy@yahoo.com wrote:

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

Re: dermel'ing
On Friday, July 7, 2017 at 10:29:44 PM UTC-4, Steve Wilson wrote:
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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)
http://www.ebay.com/itm/Moto-Tool-Drill-Press-Model-210-by-Dremel-/282561920091?epid13%24586714&hash=item41ca00bc5b:g:C~sAAOSwfIxZX-jy

Model 212
http://stevespages.com/pdf/dremel_drill_press_stand.pdf
)

Cheers,
James Arthur

Re: dermel'ing
snipped-for-privacy@yahoo.com wrote:

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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:

https://html1-f.scribdassets.com/4gf0q1x4g040fnk3/images/1-c5538e6bb8.jpg

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

http://hackaday.com/?s=pcb+drill

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)

http://hackaday.com/2010/11/29/drill-press-for-through-hole-pcb-
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

http://www.ebay.com/itm/322306928939

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.

Re: dermel'ing

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so use a large  
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proper linear rails and carriages are much much much better that that junk

https://www.robotdigg.com/product/534/Hardened-Steel-MGN12-L250-or-L350-Lin
ear-Rail-n-Carriage


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barely good enough to be a toy

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

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on  
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also use a large  
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inear-Rail-n-Carriage
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Nice.  $17 for 350mm is a deal.

Cheers,
James Arthur

Re: dermel'ing
snipped-for-privacy@yahoo.com wrote:

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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?

Re: dermel'ing

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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

Re: dermel'ing
On Sunday, July 9, 2017 at 3:09:55 PM UTC-4, Steve Wilson wrote:
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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.

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

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

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If you want CHEAP, here you go...
http://www.instructables.com/id/Easy-to-Build-Desk-Top-3-Axis-CNC-Milling-M
achine/


http://www.youtube.com/watch?v=6drMZqmyXQc


Cheers,
James Arthur
Cheers,
James Arthur

Re: dermel'ing
snipped-for-privacy@yahoo.com wrote:

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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.

Re: dermel'ing

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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?


Re: dermel'ing

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Ha. I figured it out. Easy.  


Re: dermel'ing

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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


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

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ll
  
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or  
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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

Re: dermel'ing

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Left-hand threads?  Unions?
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Re: dermel'ing
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Not hard at all with sweat fittings.  

Cheers

Phil Hobbs

Re: dermel'ing
On Sun, 9 Jul 2017 17:57:21 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

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Ah, left-hand solder!  

Copper isn't very strong.

Re: dermel'ing
snipped-for-privacy@gmail.com wrote:

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Yes, I was thinking copper plumbing would serve well instead of using  
steel pipe fittings.  

I have a fixture I made from 1/2 inch copper pipe many years ago. It has  
survived serious overload without damage and is extremely strong and  
rigid.

Making the frame out of copper pipe would be simple. You can cut it with  
ordinary pipe cutters instead of having to thread steel pipe which is  
difficult and expensive. You can assemble it for a test to see if  
everything fits before soldering it together.

Copper plumbing comes in various sizes, but the cost increases  
drastically above 1 inch:

https://www.plumbingsupply.com/copper.html

After my experience with 1/2 inch pipe, I think 1 inch pipe would  
probably be plenty good enough for the frame. After it is assembled and  
cleaned, a coating of clear Krylon spray would keep it looking nice:

http://www.krylon.com/products/crystal-clear-acrylic

This would also serve to keep PCB prototypes looking good instead of  
having to coat them with gold.

For some of us, good enough is good enough:)

Re: dermel'ing

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I should mention that making the base a complete rectangle allows you to  
use a three-point support. This means you can sit the machine on any  
reasonably flat surface and have it work without wobbling.

A four-point support will have one leg that doesn't quite hit the table,  
and the machine will wobble back and forth as the carriages slew.

Rigid and stable are the watchwords.

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