Dewalt DW735 feed roller chain-tensioner broken

[Geoff Chapman]

339635
I burned out a belt on my Dewalt dw735 planer, and when I opened up the side to replace it, I found that the chain-tensioner (lying lower left w broken screw stub visible) had snapped off, leaving its screw imbedded (its socket is the silver disc just above the left chain sprocket). I don't have the ability to extract that screw, and need to use this planer over the next two weeks before I could take it to a Dewalt service center to repair it.

Am I ok to run it as is? I tested it on a few boards, and the first (left) roller moves well enough up and down and the chain seems sufficiently tensioned as is to prevent any slippage in the sprockets. It is also clear of the drive belt by 1/8 inch or so, and doesn't seem likely to be at risk of getting caught on that. What do you all think? I'd be glad for any advice.

[Randy Viellenave]

You might consider just ordering the parts and replace them yourself. At a glance, it doesn't look to tough, I think you're looking at #104 and 107. Dewalt makes the parts PDF available, here is the link. http://servicenet.dewalt.com/Products/Detail/DW735#

[Earl McLain]

Not sure about the parts, but the tutorial on switching to a Byrd Shelix head will take you right through the remove/replace of the tensioner and drive gears. Byrd's web site i think, but PM me if you can't find it. You're already almost done--might as well finish instead of taking it to a shop.
earl

[Jack Lemley]

I installed a Byrd on mine. Taking the tensioner and associated parts off and on is a piece of cake.

Jack

[Geoff Chapman]

Randy, thanks for the link and part #'s. I'd do it if I could extract the broken off screw, which is beyond my experience, and perhaps my ability. If I drilled it out, the hole would have to be re-tapped (?) and then might be too large for the new replacement tensioner's screw(?)

[Geoff Chapman]

Jack, thanks - would be the same here except that the screw on the tensioner part snapped off and is imbedded, needing to be extracted from the hole.

[Geoff Chapman]

I saw that very good video, too, and used it to install the helix head on mins as well. But the tensioner snapped off, breaking its screw and leaving it embedded in the hole!

[mark mcfarlane]

Randy, thanks for the link and part #'s. I'd do it if I could extract the broken off screw, which is beyond my experience, and perhaps my ability. If I drilled it out, the hole would have to be re-tapped (?) and then might be too large for the new replacement tensioner's screw(?)

You can remove the sheared screw with a screw extractor and a good drill bit, both of the appropriate size. It's not a very difficult process, here is an example (https://www.youtube.com/watch?v=SMrDYJvY0Ts)

[Geoff Chapman]

I've ordered the parts (thanks Randy) and will drill and re-tap it unless I can find a way to extract it.

Back to my original question: Am I ok to run it as is? I tested it on a few boards, and the first (left) roller moves well enough up and down and the chain seems sufficiently tensioned as is to prevent any slippage in the sprockets. It is also clear of the drive belt by 1/8 inch or so, and doesn't seem likely to be at risk of getting caught on that. What do you all think? I'd be glad for any advice.

[Randy Viellenave]

I see. I saw the partial threads in the part laying down, now I realize you have the other part of that inside the chassis. If you can't wait, then I would suggest you see an auto mechanic and see if they could remove the bolt, it should just be a matter of drill it enough for an extractor, then back it out. Any old timer mechanic has removed a million broken exhaust studs. If it comes out with an extractor, it would not have to be resized and re-threaded, but if it did you could just use a heli-coil thread repair.

[Geoff Chapman]

Thanks for this Randy. I will give it a run, though the screw seems pretty small to drill and extract. I suspect I'm headed for retapping, but we shall see!

[Geoff Chapman]

Good video, Mark. Thanks. I'll give it a run...

[mreza Salav]

get some good quality left-hand drill bits and matching extractors. You should be able to get it out.

[Joe Beaulieu]

Doesn't seem like anyone is actually answering your question,. I think that the nature of that tensioner keeps only moderate pressure on the chain. I am not an engineer, but I think it would be fine to run it as is for the weekend. Run it for a while with the cover off and watch the chain. If it runs ok, go to town. I think it will be fine. Good luck.

Joe

[John Lanciani]

get some good quality left-hand drill bits and matching extractors. You should be able to get it out.

+1. Unless the screw is bottomed out in the hole or slathered with Loctite usually just trying to drill it with a left handed bit is all that is needed to back out a broken screw like that.

As for the tensioner, it looks like the chain is tight enough that skipping a tooth would be all but impossible unless you jammed the feedworks.

[Geoff Chapman]

Veery helpful feedback, guys. Thank you! I will give the left-handed drills a try when my parts come in - and will keep using it till then. This planer has been a workhorse for me for years, and glad to find over and again that it is repairable, and that there is a good community on this forum for fixing stuff like this... I'll let you know how it goes.

[Geoff Chapman]

Good news on my follow up...

While I waited for parts to arrive, I ran a couple hundred feet of lumber through the planer w/out the tensioner with no problems at all.

After parts arrived, I got a small extraction bit, used a nail set to dent the middle of the screw, drilled, it, used the extracted and out it came! New parts went in perfectly - all repaired and running. Thanks again!

[mark mcfarlane]

Good news on my follow up...

While I waited for parts to arrive, I ran a couple hundred feet of lumber through the planer w/out the tensioner with no problems at all.

After parts arrived, I got a small extraction bit, used a nail set to dent the middle of the screw, drilled, it, used the extracted and out it came! New parts went in perfectly - all repaired and running. Thanks again!

Great news Geoff. There are few things like the satisfaction of fixing something, and picking up a new skill.

[Peter Remelius]

Hi, could you help me? Trying to replace belt and can't remove bolts holding chain. Are they LH threads?
Thanks, Peter

[Ben Rivel]

Hi, could you help me? Trying to replace belt and can't remove bolts holding chain. Are they LH threads?
Thanks, Peter
Did you look through the Byrd tutorial mentioned in the beginning of this thread? If they were LH threads they would probably have mentioned that in it.