DeWalt 876 Bandsaw tension issues.

[Littleoldman]

Hello all,
I’m having a problem adjusting the blade tension on my Dewalt 786 Bandsaw. The adjustment knob on the top of the machine is supposed to move the top pulley wheel up to tighten the blade but for some reason mine doesn’t do that. You can adjust it as tight as you want but it doesn’t seem to move the pulley up or down. The spring does compress as you tighten the screw, but no movement in the pulley! Had a good look today, nothing seems broken, I’m thinking it might be the spring has given up, but I can’t see a way of getting at the spring. Anyone out there changed the spring on this type of bandsaw that could give me a few pointers? I have found a supplier of parts online and spares are a decent price. I just don’t know what bits I need to order.
I do have a copy of the manual but in this case it’s of no help. If someone needs a copy of the manual I’m happy to send it out. If more than one needs it perhaps the one I send the copy to would kindly send them the copy.

 

[Robbo3]

Manual available to download
- http://service.dewalt.co.uk//PDMSDocume ... 38_eur.pdf

I suspect that, like the 3401/3501, the threads on the tensioning bolt have stripped because they are only mild steel. Mine used to last 12-18 months. If you can replace it with a hardened version you could probably extend its life indefinitely.

Edit : Spelling

 

[Myfordman]

Just a thought. I would not expect the wheel to make any visible movement with a blade fitted.
If you are saying it does not move without a blade, then I expect there is a problem.

 

[Alexam]

If you have changed a blade, then the top knob (6) has to work in order to release the blade. You may not see this happen, but have you tested the tensin by tapping the side of the blade. The sound will change as tension alters. I had an older De-Waly when I started and it is a very slight adjustment, although, ith the threads have worn, as said above, a change of the bolt may be needed. Have you checked the bolt threads by winding the knob (6) almost off and looking inside?
Malcolm

 

[CHJ]

.....You can adjust it as tight as you want but it doesn’t seem to move the pulley up or down. The spring does compress as you tighten the screw, but no movement in the pulley! .....

If the spring is compressing then the tensioning rod threads are working,
Are you saying that the spring compresses but wheel does not follow it with no blade fitted? (doubt this is the case else you would not be able to fit a blade successfully)
If blade is fitted what is the specification of the blade,(width, metal thickness etc.) you are trying to tension?

If the blade is too thick for the machine you may just be flexing the frame rather than loading the blade sufficiently.

 

[MusicMan]

does the pitch of the sound increase (go higher) when you twang the blade when you are tensioning it? If not, it is not working, if so, it is.

 

[Littleoldman]

Thank you all for comments and suggestions, the threads on the rod seem ok and the spring tightens and relaxes as you adjust the screw what doesn't seem to happen is the steel block that has the pulley fixed to it doesn't seem to move. Got to be honest I can't work out what's supposed to happen when you tighten the screw. I remember many years ago seeing a bandsaw where the owner had fixed another guide block on the upward side of the pulleys which took up some slack from the blade. Also there's movement of about 1cm in the blade. This is a blade from Axminster and I have a feeling it might be a little longer than a blade from Dewalt. I do believe I had the same issue with the previous blade which did come from Dewalt. I'm going to order a Dewalt blade and check everything out again. Thanks for the advice will report back when I get the new blade.

 

[Harbo]

I had one a few years back and sold it on - I could never get it to cut properly.
At that time I was pretty sure the frame could not take the strain.

Rod

 

[nev]

Looking at the image here..

When you turn the knob on top of the machine the top wheel should move up or down. somewhere in the arrowed area the wheel axle will be fixed to a block or similar which in turn is connected to the up/ down threaded bolt. So with the blade off turn the knob and see whether the central block moves at all. If not it my be gunked up with sawdust and resin.

Unlikely but also check that the knob on the back of the machine (that tilts the top wheel to allow the blade to be moved in and out so the blade sits in the correct position on the wheel) has not been overtightened somehow stopping the central adjustment block from moving.

If it moves freely with the blade off but not on then as mentioned above the blade may be too wide and strong for your machine to tension. All small bandsaws have limitations as to the size (width) that they can manage. Its not listed in the user manual but apparently there is an info plate attached to your machine with the sizes etc.

You do not have to stick with DeWalt blades, any manufacturer will do, cough Tuffsaws cough