Search found 414 matches

by jim rozen
Sun Aug 29, 2010 10:54 pm
Forum: General Discussion
Topic: Electrical hookup / motor questions (P&W 3c mill)
Replies: 4
Views: 944

Re: Electrical hookup / motor questions (P&W 3c mill)

How odd, Steve. I just got done wiring up the machine you sold me, with a 3/4 hp three phase motor, and a Teco VFD. At the moment it's driven direct from the motor to the spindle pulley, no countershaft. I'm a bit short on vises (still to be purchased) but the machine cut its first metal in the base...
by jim rozen
Sat Aug 07, 2010 12:16 pm
Forum: General Discussion
Topic: hardinge 4 to 1 dividing head
Replies: 31
Views: 5524

Re: hardinge 4 to 1 dividing head

The standard hardinge universal dividing head is in fact four to one ratio.
by jim rozen
Sat Aug 07, 2010 12:11 pm
Forum: General Discussion
Topic: high pressure air compressor 3500 psi
Replies: 13
Views: 6871

Re: high pressure air compressor 3500 psi

If the volume requirements are truly that low, a bank of 1A nitrogen bottles would do the job.
You would need to fill sequentially from the bottles, don't manifold them all together. No
moving parts, no electricity required.....

Jim
by jim rozen
Wed Aug 04, 2010 2:46 pm
Forum: General Discussion
Topic: Audels Engineers and Mechanics Guide
Replies: 7
Views: 2029

Re: Audels Engineers and Mechanics Guide

The audel books are still published. Dollar per dollar I would say they are
among the best technical education out there.
by jim rozen
Wed Aug 04, 2010 2:44 pm
Forum: General Discussion
Topic: Self-Locking Taper vs Non-Self-locking Taper
Replies: 20
Views: 9589

Re: Self-Locking Taper vs Non-Self-locking Taper

"-- The joint must transmit bending and axial loads along the rods. -- There may be tension at some times -- There will likely be some vibration" This set of requirements will be fulfilled without any taper joint by the design mentioned by me above. Don't believe me? Build one and see. Take two rods...
by jim rozen
Tue Aug 03, 2010 8:04 pm
Forum: General Discussion
Topic: Self-Locking Taper vs Non-Self-locking Taper
Replies: 20
Views: 9589

Re: Self-Locking Taper vs Non-Self-locking Taper

The angle for a self-locking taper depends on the static coefficient of friction for the materials
involved. The guy lautard book gives the derivation I think.

Again a taper plus locking collar over-defines the geometery. It's unnecessary, really.

Jim
by jim rozen
Tue Aug 03, 2010 3:29 pm
Forum: The Photo Album
Topic: Black Gerstner Machinist Chest Leatherette Recover
Replies: 4
Views: 3078

Re: Black Gerstner Machinist Chest Leatherette Recover

Amazing. Only trouble is, he won't have time to shoot at all. He'll be
fielding questions from all the other marksmen about where he got that
case, and where they can get one!

Lovely work indeed.

Jim
by jim rozen
Tue Aug 03, 2010 3:21 pm
Forum: General Discussion
Topic: OT - Free Downloadable Vacuum Tube Design Book
Replies: 43
Views: 5590

Re: OT - Free Downloadable Vacuum Tube Design Book

One can build a fine one tube regen receiver using a small leaded tube like that, with nothing
more than two 9V batteries for the plate voltage. I think the A battery would be one or
two AAA cells. It absolutely would fit in a cigarette box.

Jim
by jim rozen
Tue Aug 03, 2010 3:17 pm
Forum: General Discussion
Topic: Self-Locking Taper vs Non-Self-locking Taper
Replies: 20
Views: 9589

Re: Self-Locking Taper vs Non-Self-locking Taper

You don't need a tapered connection to achive your goal. Simply bore a hole
in one rod, and step the other to fit inside with 0.001 clearance. Use
a threaded collar to draw them up. You'll need a flange on one part.

Jim
by jim rozen
Fri Jul 23, 2010 8:35 pm
Forum: General Discussion
Topic: OT - Free Downloadable Vacuum Tube Design Book
Replies: 43
Views: 5590

Re: OT - Free Downloadable Vacuum Tube Design Book

BTW, one of my first bosses was a man who did radar technology during WW2, then went on to build discrete transistor circuits, and from there to LS logic in the 1980s. He ran the physics electronics shop, and the nuclear department electronics shop, at the university of wisconsin, madison. His stori...
by jim rozen
Fri Jul 23, 2010 8:32 pm
Forum: General Discussion
Topic: OT - Free Downloadable Vacuum Tube Design Book
Replies: 43
Views: 5590

Re: OT - Free Downloadable Vacuum Tube Design Book

Randy, Kepco still makes high voltage adjustable power supplies, with current and voltage
limiting characteristics. For example, there's one in my lab that does, I think, 1KV at 50 mA.
Voltage or current limited.

Jim
by jim rozen
Wed Jul 21, 2010 3:04 pm
Forum: The Junk Drawer
Topic: End of an era
Replies: 14
Views: 2514

Re: End of an era

"So we are always paying for the people who screw up" So the number of folks who screw up has magically gone from two percent to over ten percent in the past four years? I don't buy that. Look my position is simple. If this is the real problem all you need to do is stop all entitlements, uneployment...