Jet JPM-13CS Thicknesser

A new addition to the workshop - a Jet JPM 13CS 13" Thicknesser / Moulder.

I put it through a fairly standard reconditioning procedure, which involved:

• Removing all guards and cleaning all accessible surfaces with ethanol / degreaser.
• Removing old lubricant and grime from the guide posts and the lead screwsand flushing the bearing surfaces several times with clean oil. 
• Greasing the leadscrews and oiling the guideposts.  
• Replacing stripped fasteners.
• Setting of cutterhead and roller heights. 
• Setting the drive belt tension.

It is interesting the types of problems that you find in the process... but the final result was worthwhile - a clean quiet machine, that produces a smooth planed surface, and makes less noise than the dust extractor! 

Problems

The wheels were poorly designed. The plastic wheel was attached between 3mm steel plates using a nut and bolt. These could not be tightened fully - as it would lock the wheel. Hence the bolt was also free to rotate. This really took it's toll on the bolt, especially after the wheel became jammed from the rust that was forming between the steel bushing and the bolt. This unfortunately also damaged the holes in the steel plates.

Ideally there should be a sleeve that gets clamped tightly between the steel plates, and the wheel would roll on the sleeve. I was contemplating doing this, except I could not press the existing sleeve out, or hold the curved outer surface of the wheel on my lathe...

I gave up, removed the rust from the inside of the sleeve with sandpaper, and just used a bolt with longer shoulder that spans the gap between the two steel plates - at least this way there are no threads digging into the steel. Not the greatest solution ... but there are many other things to do...

A generous coating of grease was put into the sleeve before it was reassembled.

As the tear down continued, it was discovered shockingly, that the screw holding the pulley to the cutting head was missing... The pulley was able to rock sideways by quite a significant amount.

A replacement screw was found, and a heavy duty washer machined on the lathe. 

It turns out that this was the cause of the loud roar when the machine was first switched on - it was significantly quieter after I installed the screw and tensioned the V-belts correctly. 

Setting Heights 

The cylindrical surface of the cutter head (not the blades), is to be set 1/8" higher than the infeed / outfeed rollers, as recommended by the Jet manual. The manual also recommends setting the cutter height with a pair of homemade wooden blocks. While this probably gives satisfactory results, I decided to go somewhat overboard and use 1-2-3 and 2-4-6 gauge blocks.

First I checked the parallelism of the cutter head with the table.
I lowered the cutter head down towards the gauge block (positioned on one side of the cutter head) until there was just enough clearance to slide. I then moved the gauge block to the other side and used a feeler gauge to check the clearance. The difference was about 0.2mm - not too bad.

To improve  this, the lead screws were "synchronised" by removing the chain from the lead screw's drive sprocket below the table, and adjusting the position of the screw (to raise / lower the table on that side).

The end result was a cutter head that was parallel to the table within +/-0.05mm. This was checked at 2", 3", 4" and 6" heights to ensure accuracy across the whole range of motion.

To set the infeed / outfeed rollers, a 1/8" milling parallel was used to raise the 1-2-3 block before the cutter head was lowered onto it. The 1-2-3 block was when used to set the rollers at exactly 1/8" lower and parallel to the cutter head.