CHIPMASTER belt-drive conversion

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wally318
Posts: 260
Joined: Sun Jun 05, 2011 1:06 am
Location: Kelowna, British Columbia

CHIPMASTER belt-drive conversion

Post by wally318 »

As posted earlier I asked some questions re: putting a 3 ph motor on and using an inverter only
to drop the speed as many Chipmaster owners have done when their variator goes.
So going back to the beginning my variator is not shot-it doesn't sound like a dryer full of ball bearings.
But it is loud to me, quite probably because my shop is tiny and at present the lathe sits on a wood floor
with 1/4" steel plates between the leveling feet and the floor to spread the load.
So I knew I was going to have to do something because it became increasingly annoying.

So I looked at 3 ph no dice w/o belt reduction-moot/pointless.
I looked at reeves type variable speed. Our Clausing drill press at work has that and when you
wind it up to 2000 rpm it just screams. Same problem-not a solution.
So I came up with my own solution-sort of.
So lets start with some before pics.
Pic 1 is of the original variator on the lathe on its own cast iron mounting stand/bracket with
the motor mounted underneath.
Pic 2 is the Variator speed control handwheel.
Pic 3 is with everything removed. A blank cavity so to speak.
Attachments
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wally318
Posts: 260
Joined: Sun Jun 05, 2011 1:06 am
Location: Kelowna, British Columbia

Re: CHIPMASTER belt-drive conversion

Post by wally318 »

So my idea borrowed from a lathe we have at work It's badged LANCE,
which I beleive is just a rebadging for USA sold machines.
The name they're known by is Zubal, spanish made.
The lathe has 3 pulleys on the motor and 3 pulleys on the main
spindle. And because the 3 pulleys at the motor slide on a spline
you get 7 speeds plus 7 more with the back gear.
So I took this idea and how loud it sounded when running
and said I can work with that.
So on my version I took the spline shaft from the motor and
moved it over to the intermediate shaft and that allowed me
to use a smaller pulled at the motor for a lower bottom speed.
Next I needed a way to quickly/easily release belt tension and retension.
So I came up with a sliding motor mount.
With the motor mounted on a 1/4" plate that slides in some steel channels.
The motor hung underneath a steel fabricated shelf and tension controlled
by a 5/8" leadscrew and a nut mounted to a standoff and to the sliding mount.
Pic 1 is the motor a 2 Hp Doerr farm duty, mounted to the motor mount
with the channels sitting on the sides and the leadscrew/nut asssembly.
Pic 2 are the pulleys. The motor pulley has the 2 smaller Vees made of steel with
the large pulley bolted on.
The intermediate shaft which mounts to the shelf with 2 pillow blocks
has a pc. of 1-5/8" x 6T spline shaft mounted on the end.
My new taped attachment came in very handy for this part.
Taper on the end of the 1-1/4" shaft and matching taper inside the spline shaft.
The 3-Vee pulley that slides on the spline shaft is mounted/bolted to a spline
coupling that has a flange welded to it which allows the 3 individual aluminum
pulleys to be bolted together.
Attachments
P1040349.JPG
P1040350.JPG
P1040351.JPG
wally318
Posts: 260
Joined: Sun Jun 05, 2011 1:06 am
Location: Kelowna, British Columbia

Re: CHIPMASTER belt-drive conversion

Post by wally318 »

Pic 1 is of the completed set up and everything mounted and in place
with the 2 vee pulley mounted on the end of he intermediate shaft
driving up to the clutch shaft.
And pic 2 is view of the pulleys through a front access port that I
made by enlarging the original small hole for the original on/off switch.
This was to help speed/simplify belt changes. There is also a lexan cover for the
port to keep out chips.
So you're probably asking how well does all of this work.
All things considered pretty well.
When I got the spline shaft a coupling in I was very dissapointed to see
that the 2 components had the worst fit tolerance of all those I read about
while researching this. There's press fit/sliding while not rotating fit and
sliding while rotating. And let me tell you it was a really loose fit.
My solution was to mount set screws into the splines of the coupling
12 set screws on 6 splines 1 fore and one aft. and then bore the coupling so the set
screws ride in the bottom of the female splines on the shaft and are machined with a radius
for the most contact possible.
In the slowest high range speeds its reasonably quiet but in the higher speeds it gets a bit
clackety which is amplifyed by the hollow metal stand and the wood floor.
The lathe at work has the 3 motor pulleys made of cast iron and the splines slotted into the pulleys.
For a lot less play than the spline shaft/coupling that I bought.
MY final solution will be after I finish rebuilding my Rockwell mill.
I'll machine up a pc of 1045 and mount in the dividing head and use the horizontal spindle
to gang mill 6 splines on the shaft with a very good fit and then turn down the OD after to get a snug sliding fit.
That should almost elliminate any clacketyness and noise. It should be even better than the one at work.
Because the pulleys have a quite large size range/variation several belt sizes are required to cover
all the speed combos and when using a speed in which 2 of the largest pulleys in the set come in close contact
a slightly longer belt is needed. And this lets the sliding pulley go lateral mostly when using the spindle in reverse.
Again this should be remedied with the new spline shaft.
Right now I have a handwheel for the belt tensioning sitting down in Oroville so I'm using a small vise-grip
on the outboard end of the shaft on top of a pc of split aluminum tube and slides off the shaft every so often.
The new handwheel will solve that issue and make speed changes even faster.
The best part. The speed range of this set up is 40 to 2000 rpm. 400 to 2000 in high range and divide by 10
for back gear. Not quite the 35-3000 of the chipmaster with variator.
But the lathe at work only gets 56 to 1600 rpm's and its a bigger lathe and not as rigid.
Attachments
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rklopp
Posts: 44
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Location: NorCal

Re: CHIPMASTER belt-drive conversion

Post by rklopp »

Would you sell the variator?


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wally318
Posts: 260
Joined: Sun Jun 05, 2011 1:06 am
Location: Kelowna, British Columbia

Re: CHIPMASTER belt-drive conversion

Post by wally318 »

This is the final installment for this project.
I finally got tired if waiting to get my mill done to make the new spline shaft,
with a tight tolerance fit. I went to a friends with my dividing head and
milled out the spline shaft. Right off the mill it was a bit tight.
One extra pass with the endmill on the bottom corners of each side
of the splines helped. Cleaning up the parted end of spline coupling
and de-burring all the corners as well as filing a chamfer on all the top corners
of the splines, yeilded a perfect fitting spline/coupling.
But... practical application was a bit more complicated.
At the begining of the saga, I used set screws in the spline coupling to remove
as much of the play/slop of the coupling.
So next I had to mill out the set screws.
And where the flange was welded to the outside of the coupling-so that the
3 individual aluminum sheaves could be bolted together to form a step-pulley.
The internal splines of the coupling were tight fitting, not allowing the
pulleys to slide.
A bit of cleanup on the inside of the coupling in this area as well as some filing/fitting
of the spline shaft got me the sliding fit I needed. The pic shows and end view of the fit.
I think the end result was worth it. The motor and pulleys are so quiet that the greatest noise
offender now is the timing belt from the clutch to main spindle.
At the top 2 speeds 1500 and 2000 rpm with the end cover off the belt is quite loud.
But significantly less so with cover on. The system is quiet enough to know there is
very little noise coming from the headstock/back gears. And that the gear-train only
raises its voice at the highest speed in low range-200 rpm.
Job done, now onto the next project.
Attachments
P1040398.JPG
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Bill Shields
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Re: CHIPMASTER belt-drive conversion

Post by Bill Shields »

This all looks very nice ..well thought out.

but have you forgotten that the vatiator gives you (for example) half the speed at twice the torque?

The inverter gives you half the speed at the same torque.

What do you think will happen when you attempt to take a heavy cut at low rpm?

you still have the back gears..but do not expect the same cutting performance at low motor rpms.

Everyone seems to forget that a gearbox reduces speed and multiplies torque....which a vfd does not do.
Too many things going on to bother listing them.
dml66
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Location: SW Washington State, Steelhead Country

Re: CHIPMASTER belt-drive conversion

Post by dml66 »

VFDs which support vector control, particularly the closed-loop variant, can to some degree control torque if that's more important than precise speed. I have not tried it on my drill press, preferring instead to keep the pulleys in place. It's hard to beat good ole' mechanical advantage.
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Bill Shields
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Re: CHIPMASTER belt-drive conversion

Post by Bill Shields »

Control torque.. yes...but the motor cannot output more torque than of which it is capable.

That is the basic purpose of a gearbox...which is part of mechanical engineering 101
Too many things going on to bother listing them.
wally318
Posts: 260
Joined: Sun Jun 05, 2011 1:06 am
Location: Kelowna, British Columbia

Re: CHIPMASTER belt-drive conversion

Post by wally318 »

Bill-take a look at the pics. Take a GOOD look.
Where is the VARIATOR that you're talking about?
Take a close look at all the components in the
system. It's TOTALLY mechanical-no loss of torque.
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Bill Shields
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Re: CHIPMASTER belt-drive conversion

Post by Bill Shields »

What does the thing with the big crank do in the original pictures? It changes rpm /torque in/out...it is a gearbox.. us it not? In pic 2 you call is speed control handwheel.

It may not have gears, but the functionality is the same .. constant speed in, lower speed / higher torque out.

Split, spring loaded pulleys to the same thing as gears from a force / rpm standpoint

It is not a question of loss of torque from the motor..it is a question of no multiplication of torque as you reduce motor rpm... And need more torque for the cutting application.

I fully admit that I have VFD units on many of my machines, but I never remove the step belts or other mechanical speed changing devices ..because when you need lotsa torque (more than the motor was designed to output) there is no substitute.forc a ratio change.

You may never get into that type of work, and it may not be a issue to you.. but people in general need to be careful about just dumping a gearbox in favor of a VFD.

On my vertical mill, with 3HP motor.

If I leave the step pulleys in high speed mode, then single point bore a large hole that requires the tool to run at 25'RPM...and crank the vfd down to really low rpm. .know what happens?...or use a large face mill?

Motor stalls or vfd trips on high current.

In same belt ratio.. if I set up the vfd to decelerate the motor in 3 seconds or so...similar problem.. vfd goes out on over current limit settings( which has to match the motor) or you will cook it....have to usecthevold fashioned baby brake to stop the quill.
Too many things going on to bother listing them.
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NP317
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Re: CHIPMASTER belt-drive conversion

Post by NP317 »

What VFD? I don't see one.
RussN
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Re: CHIPMASTER belt-drive conversion

Post by rrnut-2 »

Motor stalls or vfd trips on high current.

In same belt ratio.. if I set up the vfd to decelerate the motor in 3 seconds or so...similar problem.. vfd goes out on over current limit settings( which has to match the motor) or you will cook it....have to usecthevold fashioned baby brake to stop the quill.
On my mill/vfd setup, I added a braking resistor to the vfd, stopping time is about 1 sec.

Jim B
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