Blake and Duke's Knife Grinder Build

[Just Duke]

This build has been cancelled
i have just decide to just buy one.

[dragonrider]

Duke, I think over at the Home Shop Machinist Website, if you poke around you may find some folks who have built that unit or something very much like it.

[Hardcast416taylor]

Do you mean to tell me that I`ve been making knives for the last 40 odd years the wrong way, all by hand with no whiz bang power tools?Robert

[Just Duke]

Do you mean to tell me that I`ve been making knives for the last 40 odd years the wrong way, all by hand with no whiz bang power tools?Robert

No sir. My hands hurt and a machine sure helps out.

[elk hunter]

Duke,

Three phase motors are quite common and cheap. Try Craigs List and your local motor repair shops. I bought a nearly new five horse a few years ago for $25.00 in a junk shop. Made a rotary phase converter out of it.

[kirb]

I have one of the grizzly knife grinders good basic grinder started build a knife grinder from mega machine plans, should be done the end of the year. I have 2 week vacation lots of play time. I would like to have a vfd drive I have and 2 hp motor now looking for some thing better. I really like the plans that you have might be another project.

Kirb

[richbug]

Duke,

Three phase motors are quite common and cheap. Try Craigs List and your local motor repair shops. I bought a nearly new five horse a few years ago for $25.00 in a junk shop. Made a rotary phase converter out of it.

With spike in copper prices, most of those junk motors were scrapped. One local place was paying $1 a pound for them. It made it hard to justify piles of them sitting around just in case you some day got 3 phase.

[PatMarlin]

I've got a couple. What RPM do you need?

[Just Duke]

I've got a couple. What RPM do you need?

Looks like 1700 + RPM plus will work.

[PatMarlin]

I'll check. Why do you need 3 phase? Just curios.

[Just Duke]

I'll check. Why do you need 3 phase? Just curios.

So I can run variable speed? Right?

[PatMarlin]

Oh heaven's no... :shock:

You can use a VFD to run variable speed in single phase motor without all the expense.

I've got even another option- the DC variable speed motor. I've got 3hp treadmill motors that with a $85 KB Control off of ebay, you would have unlimited variable speed and they sip power.

I converted my Knee mill in the shop to run with one and it's the cat's meow. I think I had a link here. I'll go see.

[PatMarlin]

Here's a link:

http://castboolits.gunloads.com/showthread.php?t=50839

It looks more complicated than it is. I replaced the 3phase motor. That is a KB control (excellent controls by the way and great factory support). They make that control in a case version as well.

The motors I have here already have a serpentine belt pulley on them. I installed the original step pulley back on this motor, but it was a waste of time. With variable speed you don't need it.

Also- you would not need the vertical mount I had to make. They are very cool. Quiet and will run from a creep to high RPM by just turning a knob. That mill would use several amps in 3ph. With the motor swap I run it at all speeds needed, and it uses less than 12 amps in 120v. Talk about efficient. Try that with any commercial shop machine.

I'm considering installing one with CNC control on my latest CNC knee mill.

[NoZombies]

The DC motors in treadmills are great for such things. I built a few for friends using them.

I ran my personal grinder on a 3hp 100 volt DC baldor motor. It never bogged or had any real issues and I was running it at 6k feet per minute

[quasi]

HP is HP no mater what voltage. You cannot regulate the speed of a single phase AC motor with a VFD. Single phase AC universal motors can be regulated with a pot but they are to small for any serious machine.

[PatMarlin]

Huh? Have to respectfully disagree on that one.