Variable Speed Drive Upgrade to J/P

[jteneyck]

I had a thread on here a couple of weeks ago about why my MiniMax J/P bogged down taking off more than 1/32" on a 10" wide board.  Folks here were helpful in helping to diagnose the problem.  The solution was to either upgrade the 3 hp motor to something with more power or to slow down the speed of the feed rollers, currently about 26 fpm.  After considering my options, I decided to implement a variable speed drive system for the feed rollers using a separate motor.  

I did some torque calculations which suggested a motor like this one should work:



The torque rating is comfortably more than what I thought I needed, and the speed range was good.  There was just enough room in the cabinet of my J/P to install the motor.  It's a tight fit because of the lift mechanism for the planer table.  I made a template for the mounting holes of my mounting block and then drilled the holes.  The cabinet is made with 3 mm steel which presented quite a challenge to drill through, lying down and on my side, especially the large hole for the shaft that carries the sprocket.    



The motor weighs over 15 lbs, which made it a bit of a struggle to get it installed, mating it to the flexible coupling between the motor and shaft and over the mounting bolts.  But after the appropriate amount of cursing, I got it in place.  I used my CNC to cut the various pieces of BB plywood I used to make the mounting block, which was very helpful.  I glued and screwed the mounting block together.  The motor seems very solid in the cabinet.  



Looking down into the outer chamber of the cabinet you can see the sprocket the motor turns and chain.  That's a 32 tooth sprocket driven by a #410 bicycle chain, the same as the original.  The overkill 1" diameter shaft was necessitated by what parts I could find that were compatible.  The motor has a 15 mm diameter shaft.  I was lucky enough to find a 15 - 25 mm diameter coupler for it, so I used a 1" shaft and turned one end down to 25 mm to mate with the coupler.  The sprocket was another adventure.  I couldn't find a 1/8" sprocket with a 1" hub, so I ended up buying sprocket with a larger arbor hole and fitting it to a 1" hub.  Anyway, it all worked out.  


  
Here's what the chain looks like now over the planer rollers:



I was able to leave all of the original drive system in place, in case someone ever wants to convert it back.  The sprocket on the right has a chain connected to the friction wheel, but it is now disconnected from the planer rollers, so all it would do is spin if I accidentally engage the friction roller.  

The motor is controlled by a rheostat in a small box.  



I mounted it in the outer casing at the infeed side of the planer.  It looks like it belongs there.



That completed the installation.  I still have to tidy up the power cables inside the casing, but I did a test run with it to see if/how it works.  Maximum speed is now 22.5 fpm.  At that speed the motor had no trouble taking off a 3/32" bite on the same 10" board it used to struggle at 26 fpm to take off 1/32", and the new variable speed drive motor pulled the board through the planer with no issue.   I'd call it a success.  I haven't tried it at lower speeds yet, but I'm pretty sure that if I run it in the 15 fpm range I'll be able to run a Byrd head in it w/o over taxing the main motor.  The further benefit will be that even with the current cutterhead, I'll be able to take fewer passes and improve cut quality by slowing down the feed.  I'd call it a win-win.  

John

[Cabinet Monkey]

very impressive.


Just like the feed platens on a lot of widebelt sanders.

[fredhargis]

Nice solution, I was thinking a Byrd head would be more useful in a machine where it did both the planing and the jointing functions. Glad you were able to work it out.

[EdL]

My PM15-HH feeds at 20 & 16 fpm. Harder woods get fed at 16.
I also limit my depth of cut to .04. No way will I hog off stock like I used to with the old Belsaw made Craftsman.
The planer was bought lightly used about 8-10 years ago, inserts have never been rotated, the cut is just as good today as then....If a feed/stalling issue pops up, well its time to rewax the tables.
Yes, the planer has seen several thousand bd/ft of lumber over time.
IMHO, One just needs to go light and slow to benefit from the insert head

Ed

[barryvabeach]

John,  nice work,  I would guess that the ability to change speeds will come in handy as well.

[kurt18947]

Great solution and very professional looking. I don't know about any other models but I have a Jet JJP-12 with straight knives.  the straight knife model feeds at 20 FPM, the helical head model feeds at 12 FPM. I looked briefly at the the feed drive mechanism to slow it down to swap heads. It looks like a major PITA to swap drive train components though I know people have done it. I've never considered adding an alternative feed drive mechanism. Mine is going to keep the straight knives unless inspiration strikes.

[jteneyck]

Great solution and very professional looking. I don't know about any other models but I have a Jet JJP-12 with straight knives.  the straight knife model feeds at 20 FPM, the helical head model feeds at 12 FPM. I looked briefly at the the feed drive mechanism to slow it down to swap heads. It looks like a major PITA to swap drive train components though I know people have done it. I've never considered adding an alternative feed drive mechanism. Mine is going to keep the straight knives unless inspiration strikes.

It went back and forth a long time before deciding to make the change.  I think I could have implemented a mechanical speed reduction, but it would have been more work and the result would have been some lower but fixed speed.  The variable speed will assure I can adjust the speed to not overload the motor.  

The speed difference for the Jet models for straight vs. helical heads is a good indication of how much more power helical heads need.  

John