Dewalt Bandsaw DW739 Setup and Maintenance

[jimi43]

I am slowly going through my workshop tidying things and cleaning power tools and setting them up ready for a project and I am now up to my trusty DW739

I have a couple of questions if someone can assist I would be grateful.

Firstly the top wheel and tensioner assembly has always for me been a weak point of this saw. I took the tensioner assembly apart to try to see if it could be set better and the washer, bearing (thin), washer, spring assembly fell apart and dropped on the floor.

Looking at the parts list I think I know how it goes back together...basically the thin bearing goes between the two flat washers at the bottom of the plastic knob around the tensioner shaft and above the spring...am I right?

Secondly there is some crud and wear on the rubber/plastic wheel tyres and I thought these could be tidied up or replaced but it looks like you have to buy new wheels COMPLETE! Is this true? At a total of £140 for the wheels I might as well get a new saw!!! Can something been done or should I just leave them as they are...they doesn't seem to be drive problem!

Thirdly I feel that the flat bevel blade guides have always been a poor second to bearing guides seen on other saws. Can this be modified?

and lastly...are there any aftermarket fences that can be recommended for this model at the fence could do with changing. I am fed up with lining the thing up square!

Any other tips from other owners on tuning this (otherwise great) saw would be most appreciated.

Cheers

Jim

 

[9fingers]

Is this diagram any better?

http://www.mtmc.co.uk/prodtype.asp?PT_I ... istory=cat

If the blade tracks ok and does not slip then leave well alone.
Yes bandwheels for most saws are disgustingly expensive. You can make new tyres out of flat rubber belts and trade cost for labour if you wish.

Guides on this class of saw are pretty poor design. There has been a discussion on another recent thread of blocks Vs ball races and you might be able to get an aftermarket kit or just make something to suit whatever guide system you favour. I get the impression from other threads that you work metal as well as wood so this should be no problem to you.

HTH

Bob

 

[jimi43]

Hi Bob.....

Yes you are kinda confirming my view on the wheels. I thought that they may be replaceable but alas, it looks they are not.

I have had the saw for quite a time and it does get quite a workout...it was a 50th birthday present so difficult to upgrade if you catch my drift!

It might sound that I am disappointed with it and I am certainly not...(voted my best machine tool) because it opened up a new spectrum of ability for me in the workshop. It has its downsides though and the fence and guides are definitely two areas.

I can get cheap bearings and it will be a simple job to fabricate a holder from some stock brass or aluminium....I was pondering that solution before. I could probably do the same with the fence but the bits will usually cost more than an aftermarket job like a KREG...

I don't want anything complicated...just something that latches at 90 degrees every time and with a micro-adjuster. I may modify it to be like my INCA table saw fence...that is simple and works well.

Many thanks for the link and advice

Jim

 

[9fingers]

Bear in mind that even a bandsaw in a good state may well cut in a straight line but this line won't necessarily be at 90 degrees to the table edge and it will vary from blade to blade. This is particularly true with the lighter types of saw.

Your fence will need to be adjustable to cope with this.

Bob

 

[jimi43]

Bear in mind that even a bandsaw in a good state may well cut in a straight line but this line won't necessarily be at 90 degrees to the table edge and it will vary from blade to blade. This is particularly true with the lighter types of saw.

Your fence will need to be adjustable to cope with this.

Bob

I was thinking of that in my plans. I have some extruded aluminium which was from a JET fence I believe...it even has a ruler on it....I'm thinking of putting an INCAesque L-bracket at the front and back and then cut slots in this extrusion. That would give me a slide adjustment.

I usually use a very straight piece of hardwood up against the actual fence to run against anyway and use this to run against.

Thanks again for the tips and interactive discussion.

Jim

 

[jimi43]

The cleanup progresses...

Firstly the gunk came off the tyres rather well...and I have adjusted the brush that keeps the dust off the bottom wheel so that it is more effective.

I have removed the induction motor and variable speed pulley and realise that there could be a problem right from day one with this.

I need to ask if anyone knows how the variable speed mechanism actually works. Is this spring deformed or has it jumped out?

The official DeWalt blow-up parts diagram (as your link above Bob) shows an unclear part but the part appears to be a straight spring....

I therefore wonder if it has jumped out one spiral?

Any help gratefully received before I pull all this apart for no reason.

Cheers

Jim

 

[9fingers]

I see no need for anything but a simple coil spring to keep the two pulley halves pressed together. This is a perfectly standard variable speed drive.
I'd take it apart (without dropping it :lol: :lol: ) and with a couple of pairs of pliers, bend the spring back to its original cylindrical shape.

hth

Bob

 

[jimi43]

AH!! I see now Bob...the V pulley is in two halves! Of COURSE!

DOH!! :roll:

So it isn't working properly because when I turn the variable knob the two halves DON'T separate at the moment...rather they stay locked in closest together position and the belt just becomes loose!

NOW I know what is wrong with it!.....

Oh well.... a homemade curry and Top Gear and I will be on the case!

Cheers mate!

Jim

 

[jimi43]

I took the pulley halves apart and sure enough..the inbound half was jammed solid on the shaft. Hence turning the speed knob just bent the spring into the position shown above.

I have successfully straightened the spring out in a wood vise and it looks the same both ends now...although I guess it may be compromised but that is a cheap part.

The motor shaft had some but not deep corrosion on it..I think this is caused by water ingression in a damp workshop (when I first built it) in between the shaft and the bronze bushing on the inbound pulley half.

I have removed this with progressive grits of micromesh down to 12000 which is smoother than Marylin Monroe's bum now...and the pulley slides on the shaft beautifully.

I blinkin' well dropped the spring and associated washers when I released the pressure!!! DOH! But I think I have them back in the right order from the diagram!

Now all I have to do is sever my left arm for one side to tighten the motor mount while using the other arm to hold the motor up....



Watch this space and THANKS Bob!!

Jim

 

[9fingers]

Sounds good Jim apart from dropping it !!!

Write out 100 times
"I must learn not to fling critical parts on the floor when dismantling machinery"

Don't be tempted to lubricate the sliding pulley and this will A) attract dirt and jam up and B) fly out onto the belt and risk slipping.

Bob

 

[jimi43]

Ok Bob it is all back together now and my arms are sewn back. :wink:

Bob...I have a NEW saw now....I tell ya...it NEVER worked like this from new. I think the inner pulley half NEVER moved...indeed I guess it was corroded or stuck in there from day one...and in those days I knew no different...heck...it was just a bandsaw and took over from hours of painful sawing without one.

Now it goes from 330 rpm to 800 rpm and I can control the cut. I have never understood why...even with a proper metal blade..I could not cut brass....NOW....well I can't wait to try.

Another thing I have done is fix the tensioner which never really worked well either....and the blade runs much more consistently....

Boy..I tell ya....it is always worth revisiting a piece of kit that you get when a dumb git using a new toy...and...with the SUPERB logic and experience which permeates this forum...service it into a NEW toy.

Thanks mate!

Jim

 

[jimi43]

Just tried my bandsaw out on a piece of oak scrap and it is like a new tool!

The blade does not wobble...I can set the speed to optimise the cut without any burning...and it cuts really straight and true....

I am amazed that such a simple thing can have such an adverse effect on the accuracy and workings of a tool....

Thanks again for your help mate.

Jim

 

[Alf]

A happy result, Jim. I've had the Elu-badged version of this saw for years and it's an excellent saw as you say, apart from the fence and blade tension. I never did solve the first, but for the latter it's worth replacing the nut in the tensioning knob with a connecting/double nut instead - it spreads the load on the threads. From experience I can heartily recommend getting in another pair of hands to make the job of reassembly considerably less painful. Oh and fwiw, for the blade guides I replaced the metal blocks with lignum vitae - works a treat.

Cheers, Alf

 

[jimi43]

Well I didn't want Bob to think I am a TOTAL numbnuts mate....I did actually find out the hard way that under the (deceptive) tension of the plastic knob there was a rocket waiting to fire and a wheel waiting to fly off and smack you in the chops!!!!

Indeed, yesterday....I said "what complete twot designed this piece of horse do do" (edited for lethal reasons) about twn times over that...the springing pulley on the motor and the nightmare that is motor reinstallation!

Thanks for the tips on the tensioning bolt. Mine hasn't actually lost the threads yet...although I can easily see it might!

Have you had the same problem with the variable split pulley...?

I am looking forward to fitting a new blade now...with it cutting like that with a worn(ish) blade...I am hoping to be amazed with a new one!

Actually.....what blades do you use? Since you must get through many more than I, I thought you may have found some keepers?

 

[Alf]

Mine's the two speed version, so no pulley issue, thank goodness. (At least iirc - it's a while since I've actually seen it since it was entrusted to the old man's tender mercies). As for blades, last ones I got must have been DureEdge I think; they've gone kaput now as far as I'm aware. That's the problem with buying in quantity - by the time I've (slowly) worked through them the market's changed and I have to start the hunt for a good blade all over again. #-o

 

[jimi43]

Hi Alf.....thanks mate...I thought it was strange as I just did your excellent "Workshop Tour" and there - lo and behold - was a large 16" Axminster! I guessed you must have upgraded at some time.

Was this a technical improvement or just a capacity upgrade...how does the Axminster fare in comparison with the Elu. If I remember rightly...most Elu badged DW stuff was better made...i.e. the plastic/nylon bits were metal...was this true?

Loved the shop tour by the way...your evolution and trials and tribulation of ergonomic storage and use closely matches my own! I must get around to putting a tour up on my website....to frighten off anyone interested in wood!!!

My biggest fault is trying to put stuff in spaces where stuff was cleared to create a space to use stuff in the bit that was cleared in the first place!

Do you catch my drift...? :wink: 8)

Oh and if that is a Norris or Spiers in the drawer can you leave it to me in your will please....pretty please!

Jim

 

[9fingers]

Well I didn't want Bob to think I am a TOTAL numbnuts mate....I did actually find out the hard way that under the (deceptive) tension of the plastic knob there was a rocket waiting to fire and a wheel waiting to fly off and smack you in the chops!!!!

Hi Jim, I hope my feeble attempts at humour over your plight with flying mechanical parts did not lead you to think I was being judgemental. Sorry if that was the case
I'm only too happy to spend a bit of time trying to help others out whilst browsing this forum.

Glad to hear your saw is much improved after your efforts.

Bob

 

[jimi43]

Well I didn't want Bob to think I am a TOTAL numbnuts mate....I did actually find out the hard way that under the (deceptive) tension of the plastic knob there was a rocket waiting to fire and a wheel waiting to fly off and smack you in the chops!!!!

Hi Jim, I hope my feeble attempts at humour over your plight with flying mechanical parts did not lead you to think I was being judgemental. Sorry if that was the case
I'm only too happy to spend a bit of time trying to help others out whilst browsing this forum.

Glad to hear your saw is much improved after your efforts.

Bob

Hi Bob!

LOL!!!! No mate...I was equally being humourous...I guess I am still very new here...you will realise soon I have a dreadful sense of humour!

Your help has been invaluable and thanks for taking time out to help others..you certainly did with me!

Cheers mate!

 

[Alf]

Yeah, I upgraded - it was a capacity thing. I was pushing the Elu to the limit more often than not, and it was asking a lot of it. The Axminster (really just a re-badged Jet) is built like the proverbial brick structure and has taken everything I've thrown at it, so yes, it is an improvement over the Elu, but only what you'd expect given the increase in size and cost. For what it is, the Elu is still a lovely bit of kit. Can't honestly say I've been conscious of fewer bits of plastic though! Maybe when it was DeWalt badged before becoming Elu? Dunno. It's quite reasonable plastic though, except perhaps the table insert - pretty sure I made a few replacements for that over the years and kept the original just for bevel cutting.

And sorry, no Norris or Spiers for anyone in my will - I intend to take it all with me. :wink: :lol:

Cheers, Alf

 

[yebaws]

Very old thread, but you never know. I recently bought a dead dewalt dw739 on ebay and have got it going by buying a new stator for the motor. Howeve, I'm not sure I've put the pulleys together properly. It goes, but makes a lot of noise and lacks power. Maybe I've not put them together right or maybe I'm missing some washers. If you're still subscribed to this thread Jim (can't see here how to pm) and still have your bandsaw, I'd be really grateful if you could post a close up pic of the pulley with drive belt attached.

Thanks!