G0781 belt conversion

"Thanks! I was referring to the 3990"

- Ah yes, okay.

"You are right the Sieg based ones still have the plastic gears inside. I think that’s the same as the Harbor Frieght models too? "

- Yes, the HF model is just the same as the Grizzly G8689 and is, I think the oldest version of the mini mills around anywhere.

" It is interesting that after the belt conversion, if it gets too much load the belt will slip. I suppose that would be the point it would strain the gears? "

- Yes, that is the point exactly. LMS actually got the Sieg company to build their (LMS's) version of the mini mill to their own specification. A mill with the belt system will have the belt slip if it can't take the load of a hard cut as opposed to breaking plastic gears. My Taig mill works this way but I am trying to decide on a larger more powerful mill to replace it. But I do not want to have to replace broken plastic gears! To answer your question, no I am not aware of replacement metal gears for the mini mills but oddly, LMS DOES sell metal replacement gears for the mini lathes. But, those metal gears are a different design and cannot be used in the mills.

"....about the adjustment feature and getting out of tram. So far it has stayed where it is supposed to I have not had any issues with it."

- Okay, thanks that is what I was wondering about when I was considering this Grizzly mill as a future buy (but the plastic gears are a turn-off for me now that I know about them- thank you:)). I guess that locating pin in the back of the column above the big washer is helping to keep the column in place and that is a good addition to the design. The other tilt-column mills don't have it.

You shouldn't be having that problem with the gibs loosening up all the time. Are those gibs maybe too thin to fill the gap between the sliding dovetail members? I ask this because that was the case with my 9X20 Chinese lathe that I have. I had to mill new gibs to fit and I milled the new ones to fit that space as tight as I could make them while still having free movement. The original gib strips were way too narrow for a decent fit. It is great that you managed to refit your mill with a drive belt system. Good job!
 
Thanks! I am considering milling a tight fitting gib to remove any of the movement. The Z axis is by far the worst on mine.

Glad to hear you were able to make yours with success.

I was also looking at the air spring upgrade but this mill is capped off at the top and I would have to make a hole for the shock to go thru. Other than that, it would be a welcome upgrade!

Thoughts on upgrading my motor to a brushless one? Currently there is only 3 wires connecting the motor. I will have to look into this process of what all is needed.
 
Austengeist,

Earlier in this conversation you asked if metal gears were available for the X2 type mills and I said no. I was wrong about that. LMS does sell metal replacement gears for Seig type X2 mills. As a matter of fact they have different sets for both the R8 spindle type mills and another for the MT3 type spindles, but these are for the Seig X2 mills and might not fit your Grizzly. Here is the link for the R8 spindle metal replacement gear set:

https://littlemachineshop.com/products/product_view.php?ProductID=3449&category=879658189

As far as a brushless motor for your mill goes, the only company selling that type of motor/mill combination that I know of, is LMS. But that requires (again, as far as I know) a entirely different power supply/ speed control box which LMS does not appear to offer as an add-on kit for your mill. Still, you could phone them and ask them if adding a brushless motor to your Grizzly mill is a possibility.
 
Thanks for the link! I will have to send LMS an email asking the shaft sizes of those gears. I think I’ll use the motor I have until (IF) it gives out. Although some better low be torque would be nice. I’ll have to do some digging. Thanks for the help!
 
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