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VFD / Motor upgrade for Nova 1624-44 , 1.5hp or 2hp?

Joined
Nov 19, 2019
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Just got my 4th lathe in 4 years, a Nova 1624-44. Super excited with it, but now fixated on variable speed. It looks like a VFD / 3phase motor can be about half th price of the Technatool DVR upgrade of $800.
Now my question is do I put a 1.5hp 3 phase motor (MTCP2-1P5-3BD18C) and 2hp VFD for $350 or 2hp 3phase motor (MTCP2-1003-3BD18C) and 3hp DVR for a little over $400. Would I benefit from the extra hp? Both motors , from automationdirect.com seem to be the same size, I wonder if the added hp would transfer to the turning with the 8 step pulley/belt?. I am going to run 220v since it seems a better way to power it and most of the VFD units input 220v. Ideas?
 
Joined
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The motors you are choosing between are 1.5 and 2.0 HP. The lathe originally comes with a 1.5 and the DVR upgrade gets you 1.75 HP. I don't see as how 2.0 is going to overwhelm the lathe nor do I see 1.5 as under powered, but might as well go big.
 
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Richards Bay, South Africa
go for the 2hp because when yo slow it down from 60Hz to 30Hz on the VFD you are effectively going from 2hp to 1 hp. Yes you can then change the belt to get the torque back but then you are back to changing belt drive once more. I have the 16-24 and find it a great lathe , One day I'll fit a VFD/3ph motor . Until then just change the belts.
s
 

john lucas

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I just went through this with a friend. He upgraded to 2HP. However we did have problems. The motor shaft was not the same size as the pulley. The book says 7/8" shaft size and that's what we ordered. However the pulley and apparently the original motor shaft was about .080" undersize. No real problem. Took it to a machinist friend who reamed it out. Also be sure and check the motor mount. Ours looked like a 56C but was actually something like 146T although I may have those numbers wrong. My friend who is an electrician had trouble hooking up the VFD. The people at Dealerselectric.com which is where he got it were very helpful and walked him through the wiring and they found the instructions in the manual were wrong. Anyway it's working great now. We did have to program the ramp up and electric braking to get what we needed but that wasn't a problem.
 
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Well, I don't like to work on my tools, I just want to play with them. Considering how much work it would be to upgrade your motor, maybe just buy another lathe, which will be ready to go when you get it, other than assembly. I prefer more hp as well. I prefer the 3 pulley lathes to the more popular 2. Part of that reasoning is for coring. If you core in the high speed range, the variable speed lathes don't like that, and tend to trip the breaker. I found the low speed range a bit too slow for some of my smaller bowls. The mid speed range is just right. My American Beauty is a 3 speed, and was one of the very early ones. I also have a Vicmark 240, which is the one with the pivoting headstock. Love it. It has a 2 hp motor, but I can't tell if it has more or less power than my AB.

robo hippy
 
Joined
Nov 19, 2019
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I just went through this with a friend. He upgraded to 2HP. However we did have problems. The motor shaft was not the same size as the pulley. The book says 7/8" shaft size and that's what we ordered. However the pulley and apparently the original motor shaft was about .080" undersize. No real problem. Took it to a machinist friend who reamed it out. Also be sure and check the motor mount. Ours looked like a 56C but was actually something like 146T although I may have those numbers wrong. My friend who is an electrician had trouble hooking up the VFD. The people at Dealerselectric.com which is where he got it were very helpful and walked him through the wiring and they found the instructions in the manual were wrong. Anyway it's working great now. We did have to program the ramp up and electric braking to get what we needed but that wasn't a problem.

John, Thanks for that heads up, I think I read somewhere else that the Nova 1624-44 motor/pulley was slightly under 7/8. I knew I did not want 5/8 due to the "snap off shafts" from the 3000. Sounds like your friend opted to ream out the pulley?
 

john lucas

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He did ream out the pulley but that introduced some vibration due to the smaller Key way so he is having to make a new Key to lock the pulley into place better.
 

john lucas

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Well there is a key on the motor shaft a d key slot in the pulley just like it comes.from Nova. We arent 100 percent sure that's where the clicking noise is coming from but 4 of us played with the machine and the owner said it was a sloppy fit so he was going to work on it this week.
 
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I upgraded my NOVA 1624 a couple of years ago to a 2hp VFD and 2hp 3 phase motor and I made a couple of mistakes. First, I tried to ream out the pulley myself and it has pronounced runout. The NOVA motor apparently has a 22mm shaft while the new motor has a 7/8" (22.23mm) shaft. I've spent literally hours online trying to find any poly-V-5 pulley to fit a 7/8" shaft and can't find any. I read about someone sanding down their motor shaft to get the pulley to fit. That would have been a better option and would have allowed me to reverse the upgrade if I wanted to sell the lathe. Anybody have a step pulley for sale? The second problem is turning into a bigger problem. The added weight of the cast iron motor (58 lbs.) is bending the cast iron mounting bracket, as shown in the picture. Between the runout and the offset I now have very bad belt noise. I should have gone with a motor with a steel housing but I got a great deal on the cast iron motor, which is rated for severe duty and inverter rated (better insulation to withstand spikes from the VFD), neither of which is required on a lathe!
 

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john lucas

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My friend who just upgraded his 16/24 had the pully professionally reamed out by a machinist. It was not cheap but it's done right.
 
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When drilling/boring a pulley to fit a larger diameter shaft, best practice is to drill it undersized with a smaller drill bit and use a proper sized reamer bit to attain the final diameter.
You are better off being a thousandth of an inch smaller in diameter you can always heat up the pulley to slip fit it onto the shaft. This type of work should be done on
a lathe or a mill so that the pulley can be precisely held in place and then measured with a precision instrument so that the hole is centered in the pulley and aligned to
the shaft with no run-out. Cutting a small 45 degree bevel on the pulley face will also make it easier to start the pulley onto the shaft. Any slop or run-out on the pulley will introduce vibration onto the motor or spindle shaft and the belts will wear out quicker.
 
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with 3 phase power, and if you have to use a converter; The actual horsepower going through a converter, is going to be half of the rated hp on the 3 phase motor.
 
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Well there is a key on the motor shaft a d key slot in the pulley just like it comes.from Nova. We arent 100 percent sure that's where the clicking noise is coming from but 4 of us played with the machine and the owner said it was a sloppy fit so he was going to work on it this week.
A 22 mm shaft will use a 6 mm (.234" ) key, a .875 shaft will use a .187 key. From standards manual on line. You need a stepped key to adapt.
Stu
 

john lucas

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with 3 phase power, and if you have to use a converter; The actual horsepower going through a converter, is going to be half of the rated hp on the 3 phase motor.
I don' t believer your accurate in that at least not with a Variable Frequency Drive. I don't know the math but when I changed my motors it didn't appear to lose any power at normal speeds. You might lose power with a rotary converter. At one time I read up on all that but it was years ago.
 
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It is really changing from 3 power legs, to two (220); that is where the power loss for the 3 phase motor would come from. I had several lathes (olivers) that were 3 phase and built several converters; there was always a power loss on the discharge of the motor. Of course the converters they make now, may have some way of adjusting for the loss of one leg.
 
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Nov 19, 2019
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Ken,
I am the OP and the job has been done for some time and I consider it a success. My observations: I was able to sand the interior of my pulley with my drill press, making a triangular jig to keep the pulley square, a 3/4" sanding drum and lots of test fits. The key had to have a shoulder cut for the narrower keyway on the 7/8" shaft. I found a cheap diamond sanding drum kit from HF and an improvised fence for the drill press made a jury rigged metal milling device, again with lots of trial fits. If I run in the 4th or larger pulley it is quiet as a church mouse. the smaller ones cause it to slowly work out and rub on the headstock casing even though I cannot force a wobble. I attribute this to leverage on the shaft/pulley connection. The mid pulleys align with the shaft, imparting no moving force, whereas the small drive pulleys make a lot of side torque well past the end of the shaft. Compounding that s the small surface area to drive with the small pulley, then the tendency to add more tension to stop the slipping. The mid pulleys do not slip and with the 220v 3hp vfd and 2hp 3ph cast iron motor, I can run it at 1/2 (345 rpm) speed still keeping 1hp useable power.
 
Joined
Nov 20, 2014
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Minnesota
Jim,
Thanks for the reply.
First, for the pulley issue: Teknatool used to list a replacement pulley for about $100 on their website but it no longer is listed. I'll contact them directly about it. As for sanding down the motor shaft, I would power up the motor on the bench and sand it just like spindle turning. An alternative would be to have my current pulley drilled out oversized and insert a 7/8" sleeve.
Second, the motor sagging is a bigger concern for me now. I don't see any way to prop it up because I'm a lefty and constantly rotate the head to work inside bowls and HFs.
Has anybody else experienced the motor sagging problem? If so, did you come up with a solution?
 
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Apr 30, 2020
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The cast plate that the motor attaches to appears to be aluminum?
Are you saying it is twisting under the weight of the motor?
Could it be machined from steel? Perhaps thicker?
 
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Nov 20, 2014
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Tom,
The plate is cast iron and it definitely twisted under the weight of the motor. And it isn't a flat plate so it would cost more than a new lathe to machine one out of steel.
 
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Nov 19, 2019
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Ken, i didn't address the motor tilt from your post since i have not experienced it. I don't see the extra 30 lbs of the cast iron motor (assuming yours is approx 63 lb like mine) at the 8 inch midpoint it is like an extra 15 lb of torque. Tightening the belt with it in the smallest pulley would seem to generate several times that torque? Maybe the bracket could be bent back?
The pulley could be bored out and insert a 7/8 sleeve? I would like to find a 3 or 4 step 5v 7/8 pulley ranging from 1 1/4 to next to largest size. Mo
 
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Nov 20, 2014
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Well I finally got my new pulley from Teknatool and installed it tonight. I had to contact customer service to order it and got this reply:
We do have a 22mm motor pulley part #24130 for $71.10+$8.99 sh
Best Regards,

Rob D.
Customer Service Team
The original pulley is 22mm (measured it at 0.858") and the motor shaft is 7/8" (0.875"). I powered up the motor on my workbench and sanded the shaft just like working on a spindle on the lathe. After taking 0.010" off it seemed like it was very close, so I heated up the pulley to 425 deg. and it slipped right on. In retrospect I might not have had to sand anything off the motor shaft. Regardless, it worked and I have no visible runout. I used the original NOVA keyway. With the shrink fit on the pulley I don't expect to have any slippage. On the other hand, I haven't tried it under load yet.
My other problem was drooping of the cast iron motor bracket. I measured 2 deg. droop so I shimmed the bottom between the motor and the cast iron bracket with 3 layers of stick-on magnetic tape. Now it has a 1 degree rise but I like that a whole lot better.

I also added a tachometer where the pulley speed window was. My total upgrade cost was just under $300 when I purchased the parts 3 years ago.

I would be willing to share my writeup that includes all wiring diagrams and programming for the VFD if anyone is interested. Most of the information came from others so I just paying it forward.
 
Joined
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www.GrattanCreek.com
Well I finally got my new pulley from Teknatool and installed it tonight. I had to contact customer service to order it and got this reply:
We do have a 22mm motor pulley part #24130 for $71.10+$8.99 sh
Best Regards,

Rob D.
Customer Service Team
The original pulley is 22mm (measured it at 0.858") and the motor shaft is 7/8" (0.875"). I powered up the motor on my workbench and sanded the shaft just like working on a spindle on the lathe. After taking 0.010" off it seemed like it was very close, so I heated up the pulley to 425 deg. and it slipped right on. In retrospect I might not have had to sand anything off the motor shaft. Regardless, it worked and I have no visible runout. I used the original NOVA keyway. With the shrink fit on the pulley I don't expect to have any slippage. On the other hand, I haven't tried it under load yet.
My other problem was drooping of the cast iron motor bracket. I measured 2 deg. droop so I shimmed the bottom between the motor and the cast iron bracket with 3 layers of stick-on magnetic tape. Now it has a 1 degree rise but I like that a whole lot better.

I also added a tachometer where the pulley speed window was. My total upgrade cost was just under $300 when I purchased the parts 3 years ago.

I would be willing to share my writeup that includes all wiring diagrams and programming for the VFD if anyone is interested. Most of the information came from others so I just paying it forward.
Hey Ken,

I for one would very much like to see your write-up for the upgrade.

Mainly because of the price, I just picked up a used 1624-II and have been going through it, cleaning it up after a couple years of what looks like rough use.
After using a Jet 1221 SP for 1-1/2 years or so, I didn't think switching belts was going to be that big of a deal but Jet's belt change is much, much simpler.
Adding variable speed to the 1624 should make it a much more user-friendly machine.
 

Dennis J Gooding

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go for the 2hp because when yo slow it down from 60Hz to 30Hz on the VFD you are effectively going from 2hp to 1 hp. Yes you can then change the belt to get the torque back but then you are back to changing belt drive once more. I have the 16-24 and find it a great lathe , One day I'll fit a VFD/3ph motor . Until then just change the belts.
s
A minor clarification here. Within it's operating range, the maximum torque of an induction motor remains nearly constant as the frequency is changed. Changing from 60 Hz to 30 Hz would not change the maximum torque appreciably, but the HP, which is proportional to the product of motor speed and motor torque, would drop to half its original value. This is why a variable pulley system is so valuable. It lets the motor run at its max speed where the max HP of the motor is achieved, and multiplies the motor torque at lower speeds by the "gear" ratio used.
 
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For Forrest and anyone interested, here is my my documentation on my upgrade. Comments welcomed.
 

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