Jet jointer planer issue

[Kenneth Walton]

Hi,

I have a Jet JJP-12HH jointer/planer combo. Been working great for 5+ years. Recently however it started skipping when in planer mode. It gets bad enough that the chain drive for the feed rolloers will jump off if it gets going enough.

I cleaned everything, sanded the outfeed roller to make sure there was nothing stuck to it, waxed the tables, and rotated the cutterheads so they're all sharp. Any ideas what to try next?

I included a video if it helps: https://youtu.be/ZhWFAfiHQtw

[Paul F Franklin]

Check the belt(s) condition and tension.

[ChrisA Edwards]

I have a Hammer A3-31 12" J/P. Felder sells a spray product called SuperGlide. It's not cheap but a bottle lasts for a long time.

I'm still on my original bottle from over 2 years ago and it's still 90% full.

You spray a little on the platten surface before running a board through. I do this about once for every 15-20 boards, for wider boards when I notice boards not running smoothly through.

https://us.feldershop.com/en-US/en-U...=super%20glide

[Kenneth Walton]

Just checked the belts - seem nice and tight and in good shape. Is it possible the rubber out feed roller has worn to the point it’s a different diameter to the I feed roller? Or could excess roller pressure do this or something?

[Earl McLain]

I’d be inclined to follow Chris Edwards’ lead. The bed of my DW735 always looks shiny, but at the first hint of drag I stop for a coat of Johnson’s Paste Wax. Almost always solves my feed issues, and I rarely clean the rollers.
I gotta remember to try Super Glide, it gets good comments.
earl

[Richard Coers]

I'm curious to understand what you mean by skipping. If the chain comes off, it must be under tensioned? Teeth on the gears worn? Chain worn out?

[Kenneth Walton]

I waxed the tables and it doesn’t change anything.

The chain seems to be tensioned appropriately. The teeth on the cogs aren’t “shark finned”, which is how I’d tell on my bicycle if they’re worn out. I haven’t measured stretch on the chain to check roller wear, so that’s a possibility. Can you use a master link on planer chains? I’m a little out of my element.

[Steve Jenkins]

Are the sprockets held on the shafts with set screws? Could be loose

[Rich Engelhardt]

Are the sprockets held on the shafts with set screws? Could be loose

I'm no mechanic - but - that seems like a good place to look.
You can tell by the sound and the way the board sort of "skips" - something is slipping somewhere.

How does it work for you when jointing? (I'm not sure, do both use the same drive?)

[Richard Coers]

I waxed the tables and it doesn’t change anything.

The chain seems to be tensioned appropriately. The teeth on the cogs aren’t “shark finned”, which is how I’d tell on my bicycle if they’re worn out. I haven’t measured stretch on the chain to check roller wear, so that’s a possibility. Can you use a master link on planer chains? I’m a little out of my element.

There should be a master link already in it. On that size of roller chain, the teeth should already come to a point. Wear could be seen lower in the teeth guilets. Will the machine run with that guard off the chain? Run a board and see if the chain skips.

[Andy D Jones]

I don't have this model of J/P, so I'm largely going off the exploded parts diagrams (and the trouble-shooting guide) in a manual I found online.

Given the chains are jumping off their sprockets when it gets bad enough, I would look at the engagement lever (you do disengage the feed lever when jointing, right?) and while engaging it, inspect the chain tension. I'm not sure where the adjustment for the chain tension is. The parts list I found online does not seem to indicate one, unless it is the lever itself. Is the lever bent (other than by design)?

If you haven't been disengaging the feed lever while jointing, you may have a worn chain and/or sprocket(s) that need replacing.

It is also possible that one or more of the bearings in the feed roller drive train is worn (severely), allowing a sprocket to move out of position and reduce chain tension. Worn bearings on sprockets can also cause them to tilt, which can also throw a chain.

-- Andy - Arlington TX

[Kenneth Walton]

Jointing works just fine but the feed rollers are disengaged when jointing.

I do disengage when in jointing mode. The chain tensioner is a separate plastic wheel that you can loosen and tighten. While the chain tension seems fine the tension wheel is sitting at a slight angle, so that might be an avenue for me to explore when I get some shop time this weekend.

[Ronald Blue]

I'm with Richard on the chains not being tight enough. If the chain can jump off it's to loose unless the sprockets are out of alignment. Watching the video however the chain clearly acts to loose. The other possibility is if it's low quality chain it could have enough wear that it climbs the sprocket under load. I've dealt with a lot of roller chain in my job and have saw plenty of things go wrong. Yours isn't under high shock load though. With the machine off and unplugged see how much deflection it has. I just looked at the manual and it appears to have a sliding idler sprocket for tensioning. It also has more length than I anticipated. Tension is the first thing I'd look at and probably adjust. If you've never adjusted it then it's likely in need of tensioning. It actually mentions the "chain jumping" in the troubleshooting section. I would suggest 1/4"-3/8" deflection in the chain when pushing on it with a finger. It can be to tight just as it can be to loose. See how much movement it has before you change anything for reference.

[Kenneth Walton]

Well I rechecked the tension and, while on one side it was tight, on the other side it was quite loose. I was unable to tighten it enough with the idler so I think the chain is worn too much. I have a new one in order so hopefully that’s it? Everything else seemed tight.

[Ronald Blue]

You should be able to get the chain at any farm supply store or McMaster Carr or Grainger or possibly Fastenal. What is it 40 pitch?