Harbor Freight Mini Mill Motor Swap

Well, I’m new to this forum and to machining, so please try to be understanding when I ask stupid questions... here’s the first one. I just bought an HF mini mill (model 44991) and just happen to have a Shop Fox mortising machine that I no loner use/need. It has a 3/4 hp, 8 amp, 3450 rpm motor that I’d like to put on the mini mill. Whattaya think? Am I crazy, or can this work?


G'day Mr Ven. This is the forum for asking questions, no dumb questions here, the only dumb or stupid questions are the ones you never asked, we are all here to help and learn, even the most highly trained of us can still learn. I don't know much about the machine in question, other than it is a mini mill. The first question I'd be asking before fitting a more powerful and faster motor, what will you be overloading. The makers of most machines tend to put motors on them that will not overload the drive train. nor damage the structure of the machine.

Apart from the modifications that will no doubt void your warranty, will it really be worth it. What do you hope to achieve, apart from the satisfaction of doing the conversion.
 
Dave, sometimes it is just about the project.
Randy, not sure about your project list? But mine is about 10 lifetimes long. And I only have 1 lifetime to do it in. That means I’m about 9 lifetimes over booked with projects LOL...Dave
 
Randy, not sure about your project list? But mine is about 10 lifetimes long. And I only have 1 lifetime to do it in. That means I’m about 9 lifetimes over booked with projects LOL...Dave

My point is, that unlike you and I, there are some people that don't have those lists. ;) Sounds like he is just looking for something to do.
 
My point is, that unlike you and I, there are some people that don't have those lists. ;) Sounds like he is just looking for something to do.
Something to do you say? What if the folks on HM with no project list volunteered their shop time to the HM folks with too long a list. Could be a new thread on HM?
 
Something to do you say? What if the folks on HM with no project list volunteered their shop time to the HM folks with too long a list. Could be a new thread on HM?

Good luck with that. :encourage:

NOW!

Back to topic.
 
Well, I’m new to this forum and to machining, so please try to be understanding when I ask stupid questions... here’s the first one. I just bought an HF mini mill (model 44991) and just happen to have a Shop Fox mortising machine that I no loner use/need. It has a 3/4 hp, 8 amp, 3450 rpm motor that I’d like to put on the mini mill. Whattaya think? Am I crazy, or can this work?


Welcome to the forum Mr. Ven.
The HF mini mill has plastic gears in the spindle box. They would not put up with the new motor very long. LMS does sell all metal gears for the mini mill. You would also have a plastic drive gear on the spindle and one on the motor that would be a problem. You would need to adapt the motor mount and drive gears to fit. The motor controller would not work on an a/c motor. The mini mill has a dc motor. You could wire the new motor to 120 volt directly without a controller but would lose the variable speed. Some guys have used treadmill motors and controllers but it is a lot of work . LMS sells a belt drive kit. It just does not seem to be a worthwhile project. Also it could be a problem if the new motor is heavier than the original as the spindle box may not want to stay up with that extra weight. I put in the belt drive kit and air spring on mine and got rid of the two speed gears completely. I'm very happy with it. I don't know if you are familiar with Little Machine Shop but they have just about everything there is for the mini mill in parts and accessories. Great people who are very helpful.
Little Machine Shop -LMS

Roy
 
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Welcome to the forum Mr. Ven.
The HF mini mill has plastic gears in the spindle box. They would not put up with the new motor very long. LMS does sell all metal gears for the mini mill. You would also have a plastic drive gear on the spindle and one on the motor that would be a problem. You would need to adapt the motor mount and drive gears to fit. The motor controller would not work on an a/c motor. The mini mill has a dc motor. You could wire the new motor to 120 volt directly without a controller but would lose the variable speed. Some guys have used treadmill motors and controllers but it is a lot of work . LMS sells a belt drive kit. It just does not seem to be a worthwhile project. Also it could be a problem if the new motor is heavier than the original as the spindle box may not want to stay up with that extra weight. I put in the belt drive kit and air spring on mine and got rid of the two speed gears completely. I'm very happy with it. I don't know if you are familiar with Little Machine Shop but they have just about everything there is for the mini mill in parts and accessories. Great people who are very helpful.
Little Machine Shop -LMS

Roy
Roy , you stated the problems with motor conversion much better than I did.
 
Roy, you are very kind. Now I wish to address this to Mr. Ven. Please don't think that Roy and I are giving you criticism. What we are giving you is knowledge. With knowledge, you can make better decisions. That is why there are no dumb questions on this site.
 
Thanks for all,of the thoughtful commentary... I have decided to ditch the idea for now based on the potential headaches you’ve pointed out.
 
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