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Don, how are double-D holes made? I just spent 5 minutes looking at broachmaker sites and they don't have many pics. One listed it as a round shape. Do they drill a hole and fit the broach in, moving it up and down across an axis to cut the slot, or what?

Or have a friend/neighbor use his account for you, ya Luddite. :-)

-- The ultimate result of shielding men from folly is to fill the world with fools. -- Herbert Spencer

"Pete C." fired this volley in news:4f41b3a9$0$21115 $ snipped-for-privacy@newsreader.readnews.com:

Sorry. I missed the "2". Yes.

Lloyd

Like most broaching, it will be drilling a pilot hole and then pushing or pulling the broach through to finish the full hole profile. Each cutter step of the broach will progressively start from the pilot hole round diameter and expand out a few thousandths towards the final hole shape. This is why specialty broaches are long and expensive, every cutter stage is a different profile.

Thanks for the info, Pete. Broaches are almost as pricy as brooches.

-- The ultimate result of shielding men from folly is to fill the world with fools. -- Herbert Spencer

Well, specialty ones are. Ordinary simple profile ones like keyway broaches aren't that expensive.

Greenlee makes, or made a double D punch to cut holes for standard duplex outlets. They also had a 1/2" D punch for fuseholders.

What do you expect from the type who lives mostly on warm Mt Dew and stale Pizza? They only come out of their shack to pay their bills or fix yet another failed antenna . ANy time you see more than a few, they are trying to buy the latest Chinese rig for 25 cents from another cheapskate at a hamfest. ;-)

Ig,

When you bought the PICO PPMC controller, did you get the "full monte" 4- axis system with backplane, power supply, et al?

Assuming you had 4 axes of control and input, I recall your adding the rotary table. So, how did you then also handle the 5th "axis" of the spindle encoder?

Lloyd

Yes. And later I bought one more board to have 8 axes.

By adding one more board. It was actually straightforward, just buy a board and plug it into the motherboard. However, my parallel port could not keep up, which took a while to diagnose with Jon's help, and I bought a different parallel port card. They are not created equal, as it turns out.

i

Pete C. Inscribed thus:

I've used square and round files as simple broaches before now.

When I was using the printer port for general purpose I/O I found that its motherboard hardware registers have a one microsecond response time to keep the data rate on the cable within spec limits, even though the rest of the address space may respond in a few nanoseconds. I didn't check expansion cards.

jsw

Sorta, kinda. Broaches are precise profiled cutters that complete the opening from the pilot hole to the finished dimensions in a single pass generally. Rather specialized and efficient.

A "ham" who can't make up cables?

They are still pretty good here, though they are getting smaller every year. :-( Aside from all kinds of computer supplies, and intersting power supplies, I have also gotten some nice three-phase motors, a device for sliding an indicator vertically (resting on a surface plate) to carry a dial indicator to test a surface for vertical, a fixture for holding a screw and some thread pitch wires to measure the thread pitch against gauge blocks, a piece of test gear to compare current to voltage phase to tell you power factor -- or to compare two phases in a three-phase power feed and verify the phase angle, micrometers, digital calipers, a nice 24" Scherr-Tumico 24" vernier caliper, bags of 1000+ screws of some convenient size, red mushroom headed panic switches, controllers for a heat treating oven, and lots of other stuff. This is not counting all the IDC ribbon cable connectors, the bench-mount tool for crimping them, and the ribbon cable (including shielded 50-conductor ribbon cable). (Oh yes -- and last year, a nice Pace soldering/desoldering station with digital readout for temperature for each iron.)

It could have, except:

1) All voltages measured within spec -- at the backplane.

2) I swapped in a nice switching mode power supply with no change in behavior.

[ ... ]

That is what matters, after all. :-)

Again -- I would have to make the double-D broach to make them from scratch, without the old hubs to swap in.

Of course, I get similar things at hamfests. Also, last year, I got a tube of IGFETs of rather impressive current and voltage rating, at yet another hamfest. (Also a nice source for my preferred computers, Sun workstations and servers using UltraSPARC CPUs. :-)

Enjoy, DoN.

I seem to have missed the original of this, so I'll reply to the reply.

In the case of the original Tektronix gear, the hole was made by casting the hub to form it. The hub was made of Zamac (pot metal), and it had a taper on the outside to make it easier to get out of the mould. Broaches are expensive and wear, while Zamac moulds are relatively cheap and last a *long* time. Especially since the Zamac hub was used to cast a plastic gear around, instead of the brass one which I made.

However, (below is the description of how to use them. To

*make* one, I would have to start with some drill rod, turn it (between centers) to a little over the final OD, mill a pair of flats at 180 degree separation to get the double-D shape, then turn a taper on the whole thing from full dimension at one end to a round pilot at the other end which just fits the starting hole (a little larger than the across-flats dimension). Then plunge an angled cutter into the shank at regular intervals to provide a sawtooth wave profile. Then take it out, go to a heat treating oven, quench to harden, heat again to draw the temper to something strong enough to hold an edge, but not so brittle that it will break when you look at it. Then back to the lathe, cover the ways with oil soaked newspaper to protect them, and mount a toolpost grinder, and use that to take each step down to the proper diameter and clearance angle, and you finally have a broach which can be used as below to broach the D-shaped hole.

I have a collection of commercially made broaches, but they are all either square or hex -- no Double-D ones. And I've never *made* one, just studied what I have to tell me how to make one should I really need to do so.

Yes -- and you need a long travel arbor press (or something else) to drive the broach. And care to make sure that the driving force is on axis so you don't bend and snap the broach. (Better are the draw type, but they require a different style of driver -- ideally hydraulic, I believe.)

Enjoy, DoN.

Yes -- I have one of the latter -- along with a 15/32" keyed one for toggle switch mounting.

But those only are useful in relatively thin metal panels. I found that in mild steel, 16 Ga hot-rolled (which is very close to 1/16" unlike all the other gauges which don't match up to anything) was pretty much the maximum that I would risk using my keyed one in. I've used it up to 1/8" for aluminum panels, but steel is another thing. :-)

Enjoy, DoN.

That isn't uncommon in mid Florida. or do the simpleist repairs on their equipment. :(

There are a lot of gears & other metal parts needed to repair HP & Tektronix that are NLA. It could make a good side business for someone with better & more tools than I have right now.

I left Ohio in the mid 80s and made many trips to the Dayton Hamfest prior to that. It was great, till the last couple years. The motto was, 'If you can't find it at Dayton, you can't find it anywhere!'

The only Sun computer I have, came from a dumpster. A dead Ultra 10. A lot of bad electrolytics on the motherboard. It's still sitting out in themain shop, waiting for me to be able to clear off the bench & repair it.

I had both, and about another dozen stolen from my shop. It would cost about $1500 to replace them today. One of them was $541 the last time I had the nerve to look.

Thanks, DoN. Most informative.

-- The ultimate result of shielding men from folly is to fill the world with fools. -- Herbert Spencer

I like the double-d config used on bimetal hole saws.

-- The ultimate result of shielding men from folly is to fill the world with fools. -- Herbert Spencer