# Modifying gearhead mill to single belt



## Shawn_Laughlin (Aug 7, 2019)

I know there is a ton of info out there on belt conversions for gearhead mills but mine isn’t like any I have seen,at least not on the surface, but the internals may all be basically the same. 
I have a 1-1/2 hp 3 phase motor im going to install on it to replace the 3/4 hp motor, and since I will have variable speed I want to do away with the sloppy noisy gears that I believe are causing horrible finishes. I know the much bigger motor is not necessary and over kill, but it was free so I’m not going to buy a 3 phase 3/4.

My machine is a g0791 lathe/mill combo. I know rigidity was a problem before but anyone who thinks that rigidity is the cause of the horrible finish I will assure you that is not the case. I skinned the base with 1/2 steel plate and have a heavy I beam welded to that that is secured to the concrete below and the base and column are both filled with my own mixture of epoxy granite. I might add gussets to the column but don’t see much benefit bc the mods I’ve done so far have blew me away with the results. But the gearhead has so much slop, it bangs around , and twice I’ve had it lock up when the gears didn’t mesh properly. I had to switch from reverse and forward multiple time real fast to get it to unlock and that was a really uneasy feeling. 

So I’m going to replace all the gears with a single speed belt system but with a variable speed controlled motor, so I need recommendations on where to start and what is the best way to go about it? Like pilot size and belt types? Should I go with a cogged belt with cogged timing pukka or just v belts? Any help is welcome. Thanks


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## macardoso (Aug 7, 2019)

I just completed my second belt conversion on a G0704 mill that was originally a gearhead. The post can be found here. Maybe there is some helpful information.

I opted for a timing belt so I could retain orientation between my servo motor and spindle. This is unnecessary for non-servo driven equipment. Timing belts tend to run noisier than V-belts. I have seen people selecting poly vee-belts for this application and I think I would try those if I didn't need the timing belt.


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## matthewsx (Aug 7, 2019)

So I guess you didn't get any love from Grizzly about the locking up problem?

By the time you get done you'll have a completely different machine than what you started with. How about some pictures of the finish you're getting with info on the tools used and speed/feed. 3 phase with VFD control is sure nice but if the issue isn't the gears then you're right back where you started. 

John


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## Shawn_Laughlin (Aug 7, 2019)

Thanks macardoso and matthewsx. Matthewsx I will surely get some pictures for you but I can tell tooling and everything until I get off work and get home. I’m using SGS 1/2 and 5/8” 5 fluted .030 radius endmill and a “Monster I believe is the brand name  1/2” 6 flute radius but not sure the exact radius. 

I bought a couple 3/4 0 radius 4 fluted end mills from grizzly and and I’ve tried other em with 0 corner radius and they would not leave a smooth finish by no means. I’m working on some telescopic way covers right now and having to mill some hdpe plastic and even on plastic I get a horrible finish but with the em with a radius it’s much better which is understandable. But if I try to face with the sharp corner em even on aluminum the finish is rough rough. As for as feeds and speeds I usually run at top rpm of 2400, as fast as it will go and I have manually feed bc auto feed only works with lathe and that’s another reason I would like to go with the 3 phase motor and it’s own power. I would remove lathe chuck and I turn the lathe on and use the auto feed with mill then. And I’ve tried many different doc’s. Using the side of em gets a better finish and it seems to get a better finish in general when it’s loading up good and I think it’s bc the load isn’t allowing the gears to bang against each other. I wish I could upload a video on here so y’all could hear this thing sound like a metal bucket full of rocks.

You asked Grizzly well I haven’t even said anything to them about it bc I’ve had a million problems with this thing and I’m actually tired of calling and sometimes getting the guy who makes you feel like I’m the one doing something wrong. From the first shipment the box was tore open and 700 dollars in tools were gone and grizzlys contract with PayPal says they have to refund the money,they can send out replacement,well that was on May 6th and the refund was just now put back on card at the end of July. But here’s the thing i has to open a case with PayPal to get my refund after grizzly told me many times that they had already sent it out but PayPal never received $hit.  It’s funny how when Paypal said if you don’t refund him we are going take the whole purchase price of 6700 dollars out of your,meaning grizzly,account and refund it all back to him,that they refund was received by PayPal in a couple days. They were trying to pull one on me.

I had to get a new 3 jaw chuck bc jaws had a taper. The replacement was a d1-4 chuck and I needed a d1-5 and well that was a hassle and I needed a new compound gib bc the original was about an inch short. The replacement is not thick enough and only if I slide it through and about 1-1/2” stick out the other side does it take up the slop on the dovetails so you can see my frustrations. 

So the way I’m looking at it is I bought a kit that was put together but some of it needs to be taken apart and put back together while changing out some parts and modifying a little bit. That’s the only way I don’t blow up,is if I think about it like that. Sucks but I knew I knew what I was buying when I bought it. I just don’t understand bc so many people have  the g4003g which the same lathe portion I have and love it. Don’t get me wrong I do love the machine but it needs you to use some tender loving care with a little hate and cussing to get it right. Lmao.


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## Shawn_Laughlin (Aug 7, 2019)

I will say this that besides the refund which is a biggie,don’t get me wrong, and the azzho I had to deal with on the phone one time,they have actually been great to deal with.


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## Shawn_Laughlin (Aug 7, 2019)

ive got a 2 hp motor also and would like to use it on the lathe one day bc my motor makes a wah wah sound and it’s irritating to hear more than anything. Is there suck thing as a lemon lathe? Lok


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## Shawn_Laughlin (Aug 8, 2019)

Macardorso let me say that the electrical work you did is beautiful work along with the rest of it. It feels good knowing when you’ve done something that tedious, but not  just done it, but you did it right.  The rest of your build isnt anything to scoff at either. Nice work. Hopefully I can get mine up to par soon.

I’m having a new problem. I was lowering the quill and it just fell down and when I cranked the handle to try to raise it back up it wouldn’t go. I had to pick up on it so the gears would grab each other. Luckily my glass scales made it out undamaged. Well while it was extended  I looked at the quill from the side and found out why it locked up on me. The screw that’s threads through the spindle I’m guessing for the collet key or guide had backed out and got jammed between the quill and the spindle. 
I need to look at the ecploded view bc there is the quill and then what’s looks to be a sleeve and then the spindle but it rotates together and the hole that the screw went in  is misaligned and I can’t rotate it back to replace the screw,plus it’s all chewed up so Grizzly will be getting a call about that today.


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## matthewsx (Aug 8, 2019)

You can upload video, just click on the little icon to the left of the smiley face in the reply box.

Do you have the same problems with a smaller endmill, say maybe 3/8"?

John


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## Shawn_Laughlin (Aug 8, 2019)

Thank you so much Matthewsx I never would’ve noticed it


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## Shawn_Laughlin (Aug 8, 2019)

This what the screw that’s fell out and riding inside the hole  for a while and why it locked up. I will be posting a video shirtly


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## Shawn_Laughlin (Aug 8, 2019)

This is the first time I’ve turned it on since since removing the screw and it does make less rattling for sure but it still doesn’t sound right but I’ll let y’all listen and be the judges. And don’t mind the aluminum welds I was running out of gas,but wanted finish.
View attachment 3FA41D67-0E7A-47C6-BC67-CF594CE2A055.MOV


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## Shawn_Laughlin (Aug 8, 2019)

View attachment 58701206271__46C1BF12-EC80-4366-BBDF-94421A720C92.MOV


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