Belt Drive Conversion for Grizzly G0704

SEK_22Hornet

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I've seen a couple different sets of plans that could be bought to build a belt drive conversion. I decided to try my hand and designing and building my own. I purchased some XL series timing pulleys and a belt from Econobelt to work with. The driven pulley for the spindle is a 36 tooth metric bore (8mm) with a 45 mm hub. That works out to be the same diameter as the G0704 spindle, which simplifies mounting the tach wheel. The driven pulley is machined to fit over the end of the spindle in place of the tach wheel and is mounted by the same holes that held the tach wheel in place. I'll either draw this up or post more detailed dimensions once I get a little farther. Here is what i have so far.
DSCF1885.JPGDSCF1886.JPGHere are the parts that I started with. The largest one is the 36 tooth pulley. The other three are pulleys that I intend to select a drive pulley for the motor from. The black ones are 25 and 27 tooth nylon with aluminum hubs and 10mm bore, which is very close to the motor shaft size. The flanged aluminum is a 25 tooth with an 8mm bore that i would need to bore out.
DSCF1888.JPGDSCF1889.JPGDSCF1890.JPG These three views just show the un-machined pulley with the tach wheel sitting on the hub - since it is the same diameter as the top of the spindle, it will need no further machining.
DSCF1899.JPGDSCF1898.JPGDSCF1897.JPGDSCF1896.JPGDSCF1901.JPGThese views show the enlarged bore of the pulley (to clear the drawbar), the recess to center the pulley on the spindle (bored into the flat side of the pulley), the shortened hub, and the mounting holes drilled to match the holes in the spindle and the tach wheel. They also show how the tach wheel and pickup will sit on the new pulley.
DSCF1908.JPGHere are the pulley and tach wheel mounted in place on the spindle. I bored the recess that sits over the spindle to a nice snug fit so that it transfers any side force tot eh spindle directly instead of to the two 3mm socket head cap screws. Out of time right now, so I'll post more later.

DSCF1885.JPG DSCF1886.JPG DSCF1888.JPG DSCF1889.JPG DSCF1890.JPG DSCF1896.JPG DSCF1897.JPG DSCF1898.JPG DSCF1899.JPG DSCF1901.JPG DSCF1908.JPG
 
Is that a pneumatic drawbar on top? If so could you explain how it works withoit having a swivel fitting to turn at the top. I am pretty uninformed about power drawbars and would like a bit more info to help decide if one is for me or not.

Bob
 
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Nope - not a power drawbar - that's just the way it is on these mills. The drawbar is captive - the top little square is the part you have to turn to tighten or loosen the drawbar. The part that looks like a cylinder is just the cap that holds it down. It does eliminate the need to tap the drawbar to release the collet. The cap screws off if you need to pull the drawbar out for some reason.
 
Definitely interested is seeing how this comes together!
Thanks for sharing.
 
Haven't had much time to work on my project but do have a couple updates. I pulled the gear off of the motor. There is a snap ring that hold the gear on, but it is a very tight fit. I had to use a gear puller to remove the gear. The key was staked into the motor shaft.

- - - Updated - - -

The pulley has a 10mm bore, but it is too tight to fit the shaft. It would probably press on, but I don't want to take the motor apart or take the chance of damaging anything, so I opened it up to a slip fit and drilled and tapped the pulley for a 6-32 x 3/8" set screw. I clamped the pulley in the vise on my mill, chucked up a small end mill and lowered the cutter until it made a small flat on the highest point on the hub. This marked the center for me. I used center drill to spot the hole location then drilled the hole and tapped it. (If this sounds familiar to some of you, I am pretty sure i read about doing it that way here on this forum :) ) I positioned the set screw in the keyway to prevent the end from marking the shaft. Next step is making a motor mount, which I hope I will get to work on this weekend.

Dan

DSCF1912.JPG DSCF1910.JPG DSCF1911.JPG DSCF1913.JPG
 
I'll either draw this up or post more detailed dimensions once I get a little farther. Here is what i have so far.

Wow, that would be fantastic as I would like to do this as well.

I'm following your thread with very much anticipation to see your results,

Thanks for sharing-
Dave
 
I did manage to get a motor mount made this weekend but still need to take some photos of it. I need some different hardware as well. I was able to run it with the belt drive and actually made a couple small cuts, just trimming off a couple brass spacers to mount the tach pickup. Then the set screw in the motor pulley let loose, so I know I need to rethink the motor pulley mounting. I was using the nylon pulley with the aluminum hub, but I will probably end up using an aluminum pulley so that I have enough metal to cut a keyway. That presents a problem for me, since I don't have a broach. I'm thinking of using an end mill to make a cut then square it up with a file. I'll probably wait to post the pics until I have the right hardware.
 
I have some work to do on the motor pulley to get it to hold on the shaft. I'm trying to figure out the easiest way for me to cut a keyway in the bore, so I'll have to think on that for a bit. Here is the motor mount that i came up with - very basic - just 4 round spacers made from 3/4" 6061 bar stock. The motor mount plate is a simple piece of 1/4" thick 6061 plate. I'm still very much a newbie, so the not so round cut-out for the motor shaft and pulley shows my lack of experience - I need to get a flycutter.
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DSCF1919.JPG DSCF1921.JPG DSCF1923.JPG
 
I have all the hardware I need, except one set screw that should be here this week. I still need to machine a couple spacers to set the tach pickup at the right height, which won't take long. I think it is going to work out pretty nice. I'll take some final photos as soon as I get the last couple things done and put a parts list together. All of the work can be done on a mini lathe and the mill itself, unless your mill is down. Cost wasn't bad at all - probably under $100. Nothing hard to find - everything I used came form either Fastenal or Econobelt, except the materials for the new motor mount, which I got off ebay from exact_metals.

More later - Dan
 
Thanks so much for the update, Dan, looking forward to it- :))

Dave
 
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