CHIPMASTER belt-drive conversion

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Bill Shields
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Re: CHIPMASTER belt-drive conversion

Post by Bill Shields »

How big a resistor?
Too many things going on to bother listing them.
wally318
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Location: Kelowna, British Columbia

Re: CHIPMASTER belt-drive conversion

Post by wally318 »

Lets not allow this thread to run away off topic. Its not about VFD's after-all.
That topic would be better served in another subject specific thread.

Russ you're on the right track(pardon the pun)

Bill: This thread was entitled: Belt-Drive conversion
If you look at the pics you will see the motor mounted on a sliding motor mount for quick belt changes/tensioning
You will see the bracket/platform that all this is mounted to. Motor/sliding mount.
Pillow blocks for an intermediate shaft. And PULLEYS. A double smalll pulley running the speed up to the clutch.
And 2 3 step pulleys. The last pic clearly shows the pulleys, driven by a belt.
The pulley on the intermediate shaft slides on a spline shaft, Thereby 3 steps yeild 7 specific set speeds
400/500/700/900/1200/1500/2000 rpm and 1/10 speed in low range 40/50/70/90/120/150/200 rpms
A 50:1 speed ratio range all without the use of a Variator or VFD.
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Bill Shields
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Re: CHIPMASTER belt-drive conversion

Post by Bill Shields »

Well there you go...

I sometimes get off the track because I frequently see threads of relpace the motor with a VFD and solve all the world's problems.

Glad you have a way to make belt changes...
Too many things going on to bother listing them.
Bob D.
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Re: CHIPMASTER belt-drive conversion

Post by Bob D. »

To be fair Bill, you probably remembered the earlier thread by wally318 where he discussed replacing the gearbox with a VFD on his chipmaster. You and I both discouraged it. Glad to see he went with the pulley setup that retained most of the mechanical advantage of the original gearbox.
Good job.
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wally318
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Re: CHIPMASTER belt-drive conversion

Post by wally318 »

Bob your advice had more effect than you realize.
When I first bought the Rockwell mill that I'm rebuilding/modifying, I joined the Rockwell yahoo group
for some Rockwell specific advice etc. When I first introduced my self to the group, the first person to
speakup, the leader of the pack I think said-referring to my remaking the missing vertical spindle motor step pulley
:I would never have a step pulley on ANY MACHINE in my shop. Left a bad taste in my mouth.
My first thought was if you lower speed, you lower horsepower and torque by the percentage of speed drop.
I told myself no, I'm staying the course.
Everyone I asked said exactly the opposite... no problem, torque compensation etc.
So I went forward. Got rid of the 1/3 hp DC motor and controller and then Got a nice Leeson 1 hp motor
1140 rpm so dropping the spindle speed from 370-6300 to 235-4000 still respectable but with a lower bottom end.
Later on I started thinking about the practical application of doing helical milling with my universal dividing head.
Not having a swivelling table I knew it would nave to be done with vertical head and that got me thinking about bottom end speed.
I started thinking that 235 rpm wasn't low enough especially if using cutters of a large enough size in steel.
I thought even if I use the Bridgeport right angle head that I've adapted, it would let me mimic a horizontal mill
with a 4:3 ratio or 175 rpm-still too fast I thought.
So ... I rounded up a nice Reliance 3 ph 1 hp motor, but back up to 1725 rpm or 370 spindle speed.
Fast forward to the previous thread you were talking about and all of a sudden I said to myself, I think you made a mistake.
I started thinking-like I should have in the first place If you take a 1 hp motor and get 3 ph from a single ph source
you probably get 2/3 hp to start with and if you drop motor speed to 1/3 of rated to get slow enough spindle speed for say a 3 inch cutter, you see where this is going.
So.. I hadn't sold the Leeson yet. I put it back on, sold the 3 ph motor and VFD.
Then I came up with a plan to get the slow.speeds I needed from the horizontal spindle.
Using the holes that I threaded into the column to mount a slotting head driven off the horizontal spindle.
I made a bracket that mounted to these holes with an extension tube to mount the Bridgeport right angle head.
Basically re-creating a vertical head off the horizontal spindle except that it would have back-gear low speeds.
The vertical head would be tilted to the same angle as a table would be swiveled on a universal mill.
So your advice was well taken and used more than once. THANK YOU.
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