Homemade bandsaw advice needed

[dwc]

I've got it in my head that I'm going to make a wooden bandsaw this year. I'm completely out of my depth when it comes to the engineering but I'm going to try anyway, he who dares :-). I'm certainly not the first to do this and I could just buy plans online but I've decided to walk up hill backwards and do my own design (I'll be releasing the plans for free afterwards). I'm sure I'll have a few questions during the build but right now I have just two...

I've settled on using a 25mm shaft as that seems to work well in other builds but I'm not sure what shaft material to buy. For example I can buy 25mm linear ground shaft like this. I'm fairly sure that will be a good fit for bearings but I think that's very hard so I'll have trouble working it - I have no metal working equipment beyond files and a pillar drill. I can get steel round bar (for example Steel Round Bar Bright EN3B from here) which would be cheaper and I assume softer but I'm concerned about it's suitability, would it fit the bearings and would it be strong enough? I could even get just mild steel bar which seems really cheap (for example).

The other question is how do I firmly fix the wheel to the shaft? Other builds just drill a tight fitting hole through the wheel and glue it on. They also often angle grind a V in the shaft and force in a screw. This certainly works but I'd like a less permanent fixing between the wheel and the shaft. About the closest thing I can find is a rigid flange shaft coupler (example) but they only seem to go up to 14mm shaft diameters. The only thing I could find with a larger bore diameter was this but it's from the states and would cost a fortune. One promising idea was go kart wheel hubs but I couldn't really find anything suitable, they cost a lot and all had fairly small flanges. I've even looked for taper lock parts but I can't find anything suitable. I've really struggled with this part.

Thanks for any help.

[philf]

Hi & Welcome DWC.

A visit to a local scrap yard should turn up (no pun intended) a car half shaft with a suitable flange on one end and maybe even still have a bearing fitted.

What size wheels are you going for?

Phil.

[dwc]

Hi Phil, that's not a bad idea thanks I'll investigate. Cars are something I leave up to the experts so I know nothing about what's available.

The wheels will be 350mm with a centre to centre separation of 725mm for a blade length of 1552mm.

[philf]

dwc

350mm is a good size. Mine is only 305mm and a bit limiting. Are you hoping for 200mm cut?

A mate of mine used the big pulleys from washing machines for his wheels. I can't remember if he added tyres or not. The wheels were crowned. He used steel box section for his frame but clad it all in plywood.

Phil.

[dwc]

If I can get 200mm depth of cut I'll be pleased, I'm aiming for 150mm and anything extra is a bonus. While I intend to use this bandsaw I'm treating it as a learning experience to maybe build a larger machine in the future for some serious resawing. In terms of specs I'm following this Axminster saw.

I took our old washing machine apart last year and it crossed my mind to try and use the wheel from that but the hub on it was was pretty small so it went in the scrap metal pile. I'm planning on plywood wheels for this saw with rubber tires. I've got a decent sized wood lathe and a pile of other woodworking equipment so I'm on firm ground there, crowning the wheels should be easy enough.

Any thoughts on the shaft material and coupling if I don't go down the half axle route?

[timby]

Have a look on Youtube , lots of ideas on there.


https://bit.ly/3vNq5X5

[philf]

As for shaft material bright mild steel would be fine - if you had access to a metal turning lathe. You can get precision ground mild steel which should give you a good enough fit for a bearing. e.g. https://www.glrkennions.co.uk/precision-ground.html The linear shafting you linked is overkill for your application as you don't need it hardened.

As for a hub to fix your wheel to I wondered about using a pulley. I've just looked through my collection and have nothing suitable. I'm sure someone will come up with a suggestion.

I still feel the half-shaft is a possibility.

Cheers.

Phil.

[philf]

Hi Phil, that's not a bad idea thanks I'll investigate. Cars are something I leave up to the experts so I know nothing about what's available.

The wheels will be 350mm with a centre to centre separation of 725mm for a blade length of 1552mm.

dwc,

I wasn't thinking straight before when I suggested 200mm cut. Your maths is a bit out or you mistyped the length. You're a metre out.

Phil.

[dwc]

Thanks timby, I think I've watched every homemade bandsaw video on YouTube. I've taken ideas from some but I'm trying not to copy any one in particular as I want this to be an exercise in figuring it out for myself.

Phil, I mistyped the blade length, I meant 2552mm. Thanks for the link to the ground mild bar, I think that's just what I'm looking for. I'm a little bit tempted to get some bright mild bar and have at it on my wood lathe. I'm pretty sure it would be an exercise in futility but it would be fun failing - if I bought 1" bar I'd only need to remove 0.4mm which feels like it would be possible.

I considered using a pully to lock the lower wheel on as well. I need a large-ish pully on the lower axle anyway to slow things down. If I make it a taper lock and drill some holes in it I could mount the wheel to the side of the pulley maybe. Crazy idea?

I've literally just finished in the workshop building a mock up of the tensioning and tracking mechanism for the upper wheel, there should be a couple of pictures attached. The thing sticking up is supposed to be a lifting bolt with a long shank rather than some badly butchered piece of scrap ply. There's bar running in tracks in the uprights which lifts the centre section and then there's a bolt on the back for tracking adjustment. Even this monstrosity built from scrap timber and plumbing pipe held a 10kg plate and tracked it just fine.

 

 

[NormanV]

You could look up Matthias Wandel (I think that is the correct spelling) he has built a couple of bandsaws, he is currently working on a large one.

[RussellT]

Rather than try to turn down 1 inch bar to 25 mm on a wood turning lathe you'd be better off buying 25mm bright bar.

An option which would give you options on fixing wheels would be to use trailer stub axles - you could use trailer hubs to mount the wheels.  You could also look for go-kart parts - they normally use some sort of flange for mounting the wheels to the axle.

I'm looking forward to seeing your progress.

Russell

[awemawson]

You need to think how you are going to track the wheels, or at least one of them, to get the blade running true and where you want it on the wheel tyre. Just needs to be able to tilt a bit in a controlled fashion.

[dwc]

I've watched all the Wandel videos and several others, I've borrowed ideas from a few different builts. I've not seen the tracking and tensioning mechanism I'm planning on using anywhere which is why I've built a mock up.

The top wheel will be have both tracking and tensioning. In the images a couple of posts back the bolt on the back pivots the large block with the axle sticking out which should provide the tracking. The wheels will be crowned as well. You can't see it in the picture but there's a shaft running through the large central block that locates in uprights and acts as a pivot point.

I'll look again for trailer stub axles and go-kart parts. I had a look earlier today and didn't really find what I was looking for.

Cheers all, if people are interested I'll keep you up to date on the build.

[efrench]

Turning mild steel on a wood lathe isn't hard to do.  I made an 8" steel faceplate for my wood lathe using handheld HSS tools.  It would, however, be nearly impossible to accurately turn down the full length of a shaft.  Turning just the ends for bearings shouldn't be too difficult.