Author Topic: The DIY Bandsaw..  (Read 6341 times)

Offline NeoTech

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The DIY Bandsaw..
« on: August 02, 2013, 09:17:39 AM »
So basicly, i'm gonna try my hands building the bandsaw design i linked in my "Neat stuff" post..

Goals, compact 60cm throated metall cutting bandsaw, 3 speed.

Some valid questions came up there and i think they should be sorted.

Discussion points:

Drive wheels - size.
 Traditionally it seems bandsaws uses large wheels for turning the band. And the design i found didnt. Further investigation into this subject shows that the large radius wheels is mainly to reduce stress in the band itself when its running fast. If running slower speed and thinner blades, the drive wheels size can be reduced. the price you pay is versatility.

Drive wheel material.
 For a larger drive wheel you could make something out of strips of steel. If you have a roller. - i dont. So for large wheels i would have to resort to wood.. or mdf..  it still a hassle to get that perfectly round but a makeshift wood lathe could be conjoured up i guess.
Otherwise is the use of urethane casters. they are available from 100mm to 300mm and have a solid urethane gripping surface for the sawblade..

I plan to make it a full steel frame with steel door covers and sheetmetal.. Im guessing it will weigh a bit.. but is it enough..

Saw blades - for economy it seems that silversoldering your own blades is the way to go. Buying roles of half inch blade stock from ebay is dirt cheap compared to the premade ones..
For motor im aiming for a 0.75kw 3phase motor with a VFD.
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline PekkaNF

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Re: The DIY Bandsaw..
« Reply #1 on: August 02, 2013, 10:18:01 AM »
......
Saw blades - for economy it seems that silversoldering your own blades is the way to go. Buying roles of half inch blade stock from ebay is dirt cheap compared to the premade ones..

May I suggest to choose blade length that is standard anyway. You may want to buy commercial ones later on. I just bought two 6 tpi and 6/10 tpi. Most coarse ones I could find. Cost about 25 a piece, German made I think.

Pekka

Offline NeoTech

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Re: The DIY Bandsaw..
« Reply #2 on: August 02, 2013, 11:04:14 AM »
The biggest problem is then.. What is "common" standard sizes.. and how fine toothed could you get em, and in bi-metal versions ..
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline vtsteam

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Re: The DIY Bandsaw..
« Reply #3 on: August 02, 2013, 12:05:52 PM »
Neotech, what about utility metal wheels with rubber tires?

Something like this, maybe:

http://www.ebay.com/itm/2989-8-X-1-75-steel-wheel-/281010707130?pt=LH_DefaultDomain_0&hash=item416d8b1aba
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline NeoTech

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Re: The DIY Bandsaw..
« Reply #4 on: August 02, 2013, 01:27:36 PM »
Thats actually a good candidate. But then i guess we are aiming for the 4 wheel setup. I guess that could work. :)
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline NeoTech

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Re: The DIY Bandsaw..
« Reply #5 on: August 02, 2013, 01:44:52 PM »
I found these wheels if one should go with a four wheel setup.. 250mm in diameter flat contact, rubberized on steel hub with bearings

http://www.jula.se/gummihjul-med-platnav-322008
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline vtsteam

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Re: The DIY Bandsaw..
« Reply #6 on: August 02, 2013, 07:56:40 PM »
You want a slight crown across the tire rather than deaf flat, and just make sure those circumfrential grooves in the picture don't interfere with your blade. Also check out the bearings and load capacity. Should be at least equal to the sum of the blade tension vectors, plus a little allowance.

You could probably replace the bearings in some wheels if they seem cheap -- not sure about those. Your driven wheel will need to be solidly affixed to a shaft.
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline NeoTech

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Re: The DIY Bandsaw..
« Reply #7 on: August 03, 2013, 07:54:01 AM »
Crown i can do i set them up in the lathe and put some sandpaper to em. :)
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline vtsteam

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Re: The DIY Bandsaw..
« Reply #8 on: August 03, 2013, 10:21:37 AM »
Put it in the freezer first, or, if in our kinds of winter...... :)
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline NeoTech

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Re: The DIY Bandsaw..
« Reply #9 on: August 03, 2013, 11:17:12 AM »
you think, the rubber would be easier to work with if hardened up.. yeah maybe it will be. never thought of that one actually. =)
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline vtsteam

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Re: The DIY Bandsaw..
« Reply #10 on: August 03, 2013, 11:56:17 AM »
If you have to drill or machine small rubber parts, it's one way to do it. Ever try to drill a hole in a rubber stopper?

The only thing is, you have to work fast!
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline NeoTech

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Re: The DIY Bandsaw..
« Reply #11 on: August 03, 2013, 01:46:59 PM »
yeah i made a spade bit when i drilled in rubber.. works better then drills. I doesnt even need to be hardened.. =)
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline PekkaNF

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Re: The DIY Bandsaw..
« Reply #12 on: August 03, 2013, 02:23:47 PM »
The biggest problem is then.. What is "common" standard sizes.. and how fine toothed could you get em, and in bi-metal versions ..

That depends... :lol: Where you live and where you buy blades.

 I live close to this one and  they sharpen some of the wood working blades I use. They have band saw stock and do pretty much the sizes you want, but it's nice to use stock size: you need one and just pop in before 17:00 and take a box from the self.

See table in the middle of the page "Varastomitat:" sorry it's all Finnish, but I put it there just to illustrate standard sizes:
http://www.malmintera.fi/vannesahanterat_bimet.htm

Not all sizes have all tooth configurations on stock. I have 10/14 tpi and it works to about 5-6 mm thick material in my use. I have one very fine, looks like a hack saw blade, but I use it very seldom.

Pekka
« Last Edit: August 03, 2013, 04:33:42 PM by PekkaNF »

Offline NeoTech

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Re: The DIY Bandsaw..
« Reply #13 on: August 03, 2013, 03:48:47 PM »
Ah well, Sweden is the land of the retards when it comes to get hands on industrial products..  I need to call around then.
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline PekkaNF

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Re: The DIY Bandsaw..
« Reply #14 on: August 03, 2013, 05:09:51 PM »
It's pretty much the same here, but there are ways around that problem, usually you just need to ask for a"quote" and then you need exact amount of cash when you collect the stuff. But this shop is great.

Sorry, I put incomplete link on my previous post. Should have been this:
http://www.malmintera.fi/vannesahanterat_bimet.htm

I have the bog standard 4*6" band saw and it uses this blade (lenght*width*thickness):
1638 x 13 x 0,65 mm
Available tooth/inc is:   6/10, 8/12, 10/14

My saw has about 200 mm OD wheels and close to 200 mm wide cut. Throat clears close to 150 mm dia. I believe they come up with biggest  useful frame size and smallest wheels for this blade, I.E. I believe that it does not pay off to use smaller than 200 mm wheels on 0,65 mm thick blade. Two sizes up and then you are in 20 x 0,9 mm blade class. This needs bigger wheels tought.

If you know the throat you want, you'll get the location of the third wheel and there blade lenght and then choose next popular size and design on that one.

There are very many suppliers, but not all have all sizes.

This shop has lenox and list some popular sizes:
http://www.chestermachinetools.com/lenox-bandsaw-blades-5335-p.asp

Check Die Master 11 M42 Bi-Metal    13 - 0.65mm    1638mm    18    H110, HV128    BAN-B-021
at 19.24 it's pretty good and 18 tpi might be the fine tooth you are looking for. Is this size anything you are looking for?

If you go longer blades, standard is bigger blade = bigger turning radius and bigger wheels. How big throat you need?

Pekka

Offline velocette

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Re: The DIY Bandsaw..
« Reply #15 on: August 03, 2013, 06:26:58 PM »
Hi
Can I express my totally biased opinion on the construction of building a metal cutting  bandsaw.
The frame needs to be strong enough not to flex when the blade is tensioned.
Two wheels give half of the blade in contact  with the wheel.
Three Wheels need more blade tension and an heavier stiffer frame to perform.
 Four wheels would create more problems than it attempts to solve.
Take the lead from the bandsaws used in an industrial situation and find out how they are made.
What is the material and the sizes plus the amount of you you plan cut in a year.
 Eric
 

Offline vtsteam

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Re: The DIY Bandsaw..
« Reply #16 on: August 03, 2013, 09:09:36 PM »
Eric, on a 3 wheel bandsaw, like mine, the drive wheel often has nearly half the wheel in contact with the band because it is located in the acute corner of an unequal sided right triangle, at the back of the throat. Its only advantage is that it is compact vertically, at the expense of horizontal footprint. And is lighter and easier, therefore to move around.

I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline NeoTech

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Re: The DIY Bandsaw..
« Reply #17 on: August 04, 2013, 03:01:12 AM »
The frame will be welded out of 50x30x4mm tubing. And i thought i would go with a car frame approach on it. All corners will be reinforced with a tab thus minimizing flexing, then cross braze the large square parts. The overhead part is necessary though so if it would flex it would be in that backbone tubing in the throat.

But yes, more contact wheels needs additional tension, and 4 wheels need 2 tracking wheels. The benefit of 4 wheel setup would be that the tension is distributed more equal over the 4 contact points. The optimal is 2 large wheels. Out of a fabricating standpoint is 2 large wheels also the hardest to achieve.. Especially if you dont have woodworking tools. and dont own a slip roller.

I imagine a 3 wheel contact setup with two larger and 1 smaller drive wheel could be better, but it makes tracking of the band a little bit harder. i've only experiment with it in CAD so far..  And by looking at a tons of pictures of bandsaws from different manufacturers. But at such a low speed a bandsaw would move..Is it really an issue? I found several multiroller setups on metal specific bandsaws, and when it comes to the wood cutting ones they are almost always 2 wheel ones because speed necessity..
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/