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VFD conversion started

docwilson

Cast Iron
Joined
Feb 28, 2004
Location
Macon, MO USA
I finally got started on my VFD conversion. I have received a lot of help and good advice through this forum and I thought I would take some pictures and try to describe this ongoing project. I can't get the attachment window to accept my entry as it keeps telling me that this is an invalid thread. I'll go ahead and post this paragraph and see if it will let me in.
 
Well, it let me into the "manage attachments" after posting the first part of this thread, and according to the "additional options" section below this thread box, it has accepted a valid upload of my first picture. Maybe I'm just dumb, but I can't get that picture to move up into my thread reply. No matter how I try to click on it or drag it, I can"t get it to move up here where I want it. I have posted pictures in the past with no problems, so maybe some one can give me some advice.
 
What works best for me is to use the free home page that my ISP provides (most ISPs do this, but sometimes it takes a bit of prodding to find out the details). I use ftp to transfer pictures from my PC to the home page, then I just enter a URL to the pictures when I post an article.

-Dave
 
Well, it let me into the "manage attachments" after posting the first part of this thread, and according to the "additional options" section below this thread box, it has accepted a valid upload of my first picture. Maybe I'm just dumb, but I can't get that picture to move up into my thread reply.
The attachment function normally does not put photos inline within the post text. Rather it puts clickable thumbnails at the bottom of the post.

I don't see any thumbnails on yours. Perhaps in attempting to move them into the thread they got deleted.

- Leigh
 
Well, I'll try this again. Here are some pictures of my 10EE and the original motor with a splined shaft. The first thing I did was to make an alingment jack shaft to aid in aligning my adaptor plate to the transmission. It was made to the exact dimension of my motor shaft which was 1.1246". I then made a 660 bronze bushing to be a precise fit to my motor shaft to aid in supporting the armature in the steady rest. I wanted a full surface support rather than just the three support fingers of the steady. The motor I chose is a Black Max 5hp inverter rated motor that I got off of Ebay for $199. The thread won't allow me to post any more pics at this time so I'll come back again in my next reply.
 

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First of all I want to thank " Leigh" for the thumbnail advice. I was getting the thumbnails and didn't know it because you can't see them until you preview the post. I didn't feel like I was making any progress with the pictures so I never bothered to preview.
Since my original gear was splined, I followed "Toms Wheels" advice and bored out the gear to about a .0005" fit on my motor shaft. The spines came out very easy with a carbide insert bar. I then broached it in my 100 year old arbor press that I picked up for $60. The gear fit very well and was a very easy task. The last picture is the bronze bushing to be used when turning the armature in the steady rest. I haven't actually got to that part yet. More to come!
 

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To make my adaptor plate, I chose a 1" piece of cr steel. First of all I trued up the bottom and sides on the mill to use as reference points when laying out my pattern and for alignment to the transmission and motor. I then center punched my starting point to match the center line of my motor. After mounting the plate to a face plate on my CY16, I bored a .0005" fit hole to be a precise fit on my motor shaft. I then bored the .260 recess to fit the rim on my C faced motor. Next the the plate returned to the mill to drill and counter sink the mounting bolt holes for the motor. The reason to the precise shaft hole was to aid in the alignment of the plate to the transmission. The motor shaft in the last picture rotated quite easily, confirming proper alignment of my mounting holes for the motor.
 

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The last picture in the above post also shows the transmission mounting holes which will be described in this post. I already had my jack shaft made, so now I made an Al bushing to insert into the back of the transmission. With the sliding gear inserted into the "high range" gear in the front plate of the transmission, the bushing gave me a very precise means of aligning the jack shaft. The two alignment dowels on my transmission both had little tits on them, just like a center punch. By inserting the jack shaft thru the mounting plate and the Al bushing and into the gear that was positioned into the "high" gear, I was able to orient my mounting plate quite accurately to the tranny. A light tap with a hammer center punched the position of the locating dowels onto the plate. This was all done with the transmission mounted to an angle plate, so that the botton edge of the plate which was true to the mounting feet of my 184TC motor, would also be true to the mounting feet of the transmission. The alignment dowel holes were then drilled into the plate. With the tranny aligned with the jack shaft and dowels, the transmission mounting bolt holes were punched, drilled and tapped.
 

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With the transmission mounted to the adaptor plate and motor, there was just a very light resistance to turning the pulley with finger pressure. Since both the sliding gear and mounting plate were bored with only.0005" clearance, this confirmed proper alingment. The plate will later on be opened up for more clearance and counter bored for an oil seal.
The shaft extension itself was turned and threaded on the lathe out of 1045 as suggested by Harry. I went ahead and copied his suggestion of a 5/8 -13 thread with a locating shoulder. The end was left about .020 over to allow for final fitting once inserted into the armature. I'll be back with more.
 

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Thanks for the photo's of your progress. Nice to see you moving along quickly with the conversion. The end result will be worth it, when the 10EE makes chips again.
 
I think this is the right way to go about a conversion -- leave the adapter plate larger than needed, and go with a rectangular shape.

After everything has been fitted to perfection (your shop's, that is) the plate may be scribed to the transmission (there are several variations, so no one adaptation is likely to be identical to the next) and is cut using a bandsaw just outside of the line, and is thereafter ground to the line, using, say, a combo 12" disk and 6 x 48" belt finishing machine.

As most know, I am partial to preservation of the dc drive, when feasible, but with the advent of sensorless vector drives, and vector drives which have a provision for tachometer feedback, in an affordable 5 HP size, possibly also single-phase without derating, conversions are becoming more and more the path of least resistance.

I am still not convinced that threading of the shaft extension is a requirement. Rather, a light press fit, made permanent with Loc-Tite and a tapered pin, should be more than sufficient.

After all, the extension is not supporting much of the input gear, that gear being supported mostly by the actual shaft, not the shaft extension.

However, for more than practical reasons the shaft extension has to be machined for the key, or the input gear's internal key has to be truncated so it won't engage the extension.

I was scanning some "ePrey" auctions for suitable 5 HP motors, and one in particular featured a 1-3/8" shaft.

Usually, 1-3/8" shafts are long enough without having to deal with an extension, but motors with those shafts are rare.
 
vfd conversion started

Peterh, I looked into using a motor with the 1 3/8" shaft but decided against it because I didn't think the inner part of the two piece gear had enough meat in it to bore it out that much. By the time you bored it out and then broached the keyway, there would not have been much left in the key area. It certainly would be easier than altering the armature on a 1 1/8" motor.
 

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I wasn't suggesting using the 1-3/8" shaft as-is and boring the gear out any farther, rather my intention was to turn the motor shaft down to 1-1/4", and using the gear as-is. This works for the keyed gear incarnation.

For the splined gear incarnation, the 1-1/8" shaft, plus an extension, and boring the gear out to 1-1/8" remains the recommended option.
 
Splined VS Keyed Gear

Well, I'll try this again. Here are some pictures of my 10EE and the original motor with a splined shaft. The first thing I did was to make an alingment jack shaft to aid in aligning my adaptor plate to the transmission. It was made to the exact dimension of my motor shaft which was 1.1246". I then made a 660 bronze bushing to be a precise fit to my motor shaft to aid in supporting the armature in the steady rest. I wanted a full surface support rather than just the three support fingers of the steady. The motor I chose is a Black Max 5hp inverter rated motor that I got off of Ebay for $199. The thread won't allow me to post any more pics at this time so I'll come back again in my next reply.

I've just begun to refurbish my 10 EE and am currently working on the gearbox retrofit. When I looked at the bull change gear on my machine, it's already set up with a key slot in it. I'm in the process of adding the plate, drive shaft, bearing, oil seal, and a spider coupling to couple to my motor. My machine had many layers of paint on it (about 3/16") and I've been stripping them with "Zip Strip." I priming, spot-puttying, sanding and repainting everything. It's like doing body work on a car! It's slowly begining to look like a brand new machine.
 
magsight
Tell me more about your retrofit. Where does the spider coupling come in? Are you using the DC motor end bell that mates to the gearbox and coupling an AC motor onto the remains of the DC rotor shaft (or a shortened copy)?
RKlopp
 
vfd conversion started

Here comes the armature part. First I centered up the armature, using the bronze bushing that I had made previously, in the center rest. The armature was then faced off, drilled for the threaded end and then bored to be a light press fit for the turned locating shoulder on my extension plug. The threads were 5/8 x 11 x .400. The locating shoulder was .625 x .400. The extension was then screwed in with red loctite. At that point I center drilled the extension and turned it down to match the 1.1246" diameter of my motor shaft. The bronze bushing worked very well and the gear slid onto the shaft with a nice snug sliding fit with no hand fitting required at all. The extension itself was .900" long so that the shaft would extend into the transmission the same distance as the original DC motor shaft. The most difficult part of this step was bottom tapping the 5/8 threads.
 

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I think you'll get along easier than me on the 5hp black max. I put a 7.5HP black max with the encoder ion my 1959 square dial 20" and had to do some major surgery on the ribs in the base to get everything to fit in the right place. I even had to notch the drawer from the wiad.... the encoder hit it. The 7.5 has a lot of guts... I don't think I have ever put it in back gear since I got it done, but heavy work is done on a much larger machine. I went with a hitachi sj300, but if I had to do it again I have had better success elsewhere with the altivar 71 drive from square D.
 
vfd conversion started

The armature was then transferred to the mill, and the keyway was cut into the extension. I then cut the necessary length of keystock which happened to be +.002. Because the key was oversized, I used the surface grinder to remove .002 from the top of the key and .001 from the top half of each side of the key. This made for a very nice press fit of the key into the shaft and a perfect sliding fit of the key in the gear. I didn't plan it this way, I just didn't have any nominal key stock on hand. It looked like a inverted T when pressed into the shaft. The key and shaft was then drilled and tapped for two 4 x 40 x 3/8 retaining screws. I also drilled a hole so that I could use a 1/8 roll pin to aid in retaining the extension itself. The key was not permanently placed at this time because I still had to reassemble the motor. After assembly of the motor the gear was checked again for proper sliding fit. So far so good.
 

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