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Replace Vari speed drive with VFD and fixed pulleys, Seiko clone.

Overland

Stainless
Joined
Nov 19, 2017
Location
Greenville, SC
Simple question, and maybe an obvious answer, but maybe I can learn from someone else's experience.
On the vari speed there's no provision for belt tension.
So, I'm use "B" belt pulleys from Wood's that are used on A/B section pulleys.
I've calculated the belt length from the pulley datum's.
The belt will sit quite low in the pulley.
I'm really not sure how I'm going to assemble this drive and get the motor bolts in, with the necessary tension.
Should I file the motor bolts holes out to a slot ?
Please share any experience.
I've rotated the head so the motor is siting upside down on the knee.
Thanks in advance.
Bob
 
Hey dude, take it easy.

I'm just an observer here but I think your wording assumes that a reader knows your situation. A picture might help.
 
Let me add something......
I have a Seiki (or Seiko) Bridgeport clone.
The variable speed belt system is worn out, so I'm replacing with a VFD and fixed belts.
My question is the motor is currently in a fixed location, because the belts are automatically tightened with the variable drive.
So has anybody done this, and how did you arrange for belt tightening please ?
Thanks,
Bob
 
Ahh good, I can ignore this now as it’s clearly not Hardinge related.

Good Luck with finding a solution to your dilemma!


Sent from my iPhone using Tapatalk
 
When I did my Bridgeport BOSS mill, I found that the flange on the stock motor was not a standard C face, so I needed an adapter anyway, since I was changing to a bigger motor. So, I made an adapter out of 5/8" aluminum plate (thick enough to bury the heads of the SHCS that hold it to the belt housing) and slotted the holes for the bolts into the C face. Doesn't take much, I think I slotted the holes 1/2". The Bridgeport belt housing has a removable cover opposite the motor, so the bolts are accessible.

Dennis
 
Is this like your deal?

Seiki XL

Get a 1/2" thick aluminum plate and drill it for the motor bolts. Usually 4 holes. Slot one side hole. The stock BP is made like this.
 
Yes, that's my machine.
Got an adapter plate in the works, and some nice cast iron pulleys.
I'm gearing it so the motor runs at 60 hz for a 3" facemill; about the highest power demand I need.
Thanks,
Bob
 
We have a Taiwan clone with a head that looks very similar to that Seiki. The Reeves drive on ours is noisy and I considered a VFD conversion as well. However, after looking it over, I saw the pulley hub on ours, part #70 in the picture, is splined whereas the Bridgeport's are keyed (I think). My concern is how well a pulley would fit and stay in place on the splined shaft vs a regular keyed shaft. Even with a QD taper lock bushing I'm not sure there is enough contact surface to be reliable.

Is your hub splined or keyed?

head assembly.jpg
 
I have a Reeves that works. I was too afraid I might break it if I attempted to take it apart. So I soaked it in rust remover and some brown muck
came out of the pulley slide area. I lubed it a little and it works fine. The reason for the soak/tear-down was that it was sticking. But the Hardinge
door emblem says to run entire speed range daily. I don't do that.
 
Shaun,
The spindle on my mill is a plain diameter where the moving part of the cone sits. 35 mm from memory.
The fixed part of the cone sits on a slightly larger dia. I tried to remove it with a puller, heat etc. I moved it about 1/16th after a lot of effort and noticed the spindle bearings become tighter. Didn't really understand why, but figured I may do some damage, so I pushed it back on and will leave it there.
I'm using Woods steel/iron pulleys. 4" on motor and 8.5" on spindle to give me 800 rpm at 60hz, for max power for 3" facemill.
I'm a little concerned with the weight of the pulley on the spindle, 8 lbs, hopefully not an issue.
 
I used a c frame motor, and CNC plasma cut a motor mount, I used low profile socket head cap screws and recessed the bolts so they will clear the top of the machine and then had 2 slotted holes to mount to the original bolt holes. I made a plate for the back of the machine with a threaded rod that is welded to the motor mount so you can tension the belt and then lock the bolts. I used a 184TC mount 5hp motor.

And it is all driven by a 10 grove j section serpentine style belt.


I just finished the machine and have not run it yet ill post some pics if you interested.
 
Thanks Bugman.
I used a face mounted motor and got a simple 1/4" plate plasma cut with various holes and a slot for belt adjustment. Then used countersink head screws to hold motor. Nothing fancy for adjustment; just a screwdriver to tension while I tightened up the screws.
Works well.
Bob
 








 
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