USAPyro's Guide to Harbor Freight Ball Mill Modification

[usapyro]

I just redid my mills properly today with more than just tape rings to expand the rollers.

 

http://i50.tinypic.com/1531d9t.png

 

Step 1. Make 2-3 rings around your drive roller with black tape the same as the inside diameter of some PVC pipe. (You can use a different type of pipe too.) For the 6lb model use 3 rings. I wrap the tape onto the rods with the ball mill turned on. It goes VERY fast...

Step 2. Take off your mill's roller rods by popping off the metal clips at the ends using two needle nose pliers unless you have the proper tool.

Step 3. Fit the PVC pipe over the tape rings and make sure it fits as snugly as possible on each one. Add/remove tape as necessary. ALIGN the pvc pipe in it's proper location and double check to make sure it's correct. Put it back into the machine to check if necessary.

Step 4. Get your hot glue gun real hot and place a solid circle of hot glue up against the black tape at the ends. You want the hot glue to bond to the black tape and the PVC. Bonding to the metal rod with it's clear plastic wrapping isn't important.

Step 5. Put it all back together!

 

Last step... Expand the other roller by hand to 3/4th of an inch with 2 or 4 black tape rings spaced accordingly depending upon the model. If you expand the drive roller to 1" O.D. then 3/4" O.D. is all you need on the non drive roller... It will balance the weight back onto the drive roller enough so there is no slippage. If there still is slippage use some light sandpaper on the outside of the PVC to roughen it.

http://i47.tinypic.com/seywp3.png

 

To prevent your motor from burning out I would recommend 2-3lb's lead and 150-200g composition per jar. I personally use just over 2Lb's lead and 200g composition with a 1" O.D. drive roller in my 3Lb jars on these mills. PERFECT black powder in 20-23 hours. With 150g composition in the mill it's perfect in around 14 hours. I kinda like having my milling time at around 23 hours. I can do back to back runs day after day on a perfect schedule.

 

 

Tip: I would recommend against expanding the non-drive roller with pipe and just use black tape rings to expand it. The non-drive roller having less weight is more efficient!

 

Tip: Lubricate the joints on these mills with a single drop of lighter weight gear oil each... It helps.

 

 

Why is it better to have a higher speed barrel? The lead will nearly always be tumbling instead of rolling. It will also be falling from a higher height! This results in more crushing force and much finer and hotter black powder!

Edited October 20, 2012 by usapyro

[brimstoned]

I'm definitely going to run my mill time up from five hours, and may expand my rollers too;

my BP is ok for many things, but pretty mediocre for lift.

 

...or maybe try a different C? I've been using cedar that I roasted a decade ago.

Edited October 23, 2012 by brimstoned

[Bobosan]

Hi. I'm new to the forum so please forgive if I step over a line here. I modded my six pounde mill roller using auto heater hose slipped over the drive roller only. It was a loose fit so used some silicone caulking to help with gripping the original tubing. The upgrade plans on Skylighter use a larger PVC tubing but couldn't find any with the right wall thickness.

 

While I had it apart I replaced all four nylon bearings with oilite bronze ones. There was so much wear slop that the rolling motion was becoming erratic and started to break belts more often using one drum at a time. The bronze bearings were cheap and easier to get than the original ones.

[Short5]

Hi. I'm new to the forum so please forgive if I step over a line here. I modded my six pounde mill roller using auto heater hose slipped over the drive roller only. It was a loose fit so used some silicone caulking to help with gripping the original tubing. The upgrade plans on Skylighter use a larger PVC tubing but couldn't find any with the right wall thickness.

 

While I had it apart I replaced all four nylon bearings with oilite bronze ones. There was so much wear slop that the rolling motion was becoming erratic and started to break belts more often using one drum at a time. The bronze bearings were cheap and easier to get than the original ones.

Good idea on the bronze bearings! I found the tube suggested in Skylighters upgrade plans at the local Home Depot. It worked perfectly.

[mabuse00]

While I had it apart I replaced all four nylon bearings with oilite bronze ones. There was so much wear slop that the rolling motion was becoming erratic and started to break belts more often using one drum at a time. The bronze bearings were cheap and easier to get than the original ones.

 

The pastic bearings are a disgrace.

How did you realise the bearing housings?

[Bobosan]

Found these on Amazon;

 

http://www.amazon.co...ils_o01_s00_i00

 

and then had to turn down the diameter to fit into the ball mill frame. Oilite bronze works easily. I just tightened the bearings on a bolt with a nut and chucked it in a drill and used a file to work the diameter down to fit snugly in the mill frame.