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Old 11-06-2015, 02:15 AM   #1
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Default Small bandsaw mod to cut steel

I have a small bandsaw that i used for cutting timber up to 3" thick
Now i used it more for cutting metal,will cut up to 70mm thick alum
and 25mm brass with ease but too fast for steel.The blades i was using are cheap quality from the local hardware store and touching steel just took the edge right off.I found a new supplier and twoo blades were ordered,cheaper and better quality.The invoice stated they were suitale for cutting steel but at a recommended speed of 300fpm.My machine had a speed of 2300fpm
I read a post by Brian Rupnow where he had added extra drive pulleys to his bandsaw to reduce the cutting speed.Could i do the something similar ?
the 150w motor ran at 1450rpm from a 17t pulley to a plastic 26t pulley fitted to the 240mm dia blade wheel.I checked and decided that although very tight i could squeeze in an additional idle pulley.I made 3 new pulleys 15t,40t and 48t
The existing 17t was modded and repositioned on the motor shaft,the 15 and 40t were bolted together with a roller brg and fitted on a new idler shaft
the 48t pulley was bolted to the blade wheel.I bought a new 65t belt and reused the existing.Very tight and tricky.
Result motor 1450rpm x17/40 = 616rpm
616 x 15/48 = 193 rpm=475 fpm still a touch fast but works well
Cuts thru 12 thk steel plt slowly but with ease.Ok for alum and brass
and still ok for timber,slower but much more torque,no bogging down aS YET


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Old 11-06-2015, 03:02 AM   #2
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Nice job on the conversion !

Brian


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Old 11-06-2015, 01:11 PM   #3
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I have the same bandsaw and have been wondering about modifying it for some time.

In fact a while ago I posted a question.

Question answered - now to get my A in G and make the mods.

Thanks for the post.

Regards,
Ken
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Old 11-06-2015, 02:31 PM   #4
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What make and model of bandsaw did you modify?
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Old 11-06-2015, 08:57 PM   #5
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Good stuff Bazmac!!! I really like your non-slip pulleys.----Brian
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Old 11-06-2015, 11:15 PM   #6
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the existing drive was with a toothed belt.Std section 9mm wide x 5mm pitch
I ground a simple single point tool as shown.The sizes were determined by
physical constraints and ease of the homemade deviding head,using the existing belt and a new one the same size gave me ctres etc that would just fit
Quite surprising how easy it was to make the the simple timing pulleys
Would be ideal to replace gears/sprockets etc on models
The bandsaw is a simple Draper 10" model that i brought from the UK Works well for its size.Any cheap model from the local hardware store would work well for $100 or so.Its main benefit for me as i have mentioned before is
its light weight,i just pick it up and use/store it where i want.Now only time will tell,i need to get cutting steel and see how long the blades last,torque seems much better and no bogging down.It seems a bit tight at the moment,if the belts dont stretch a tad i will have to look at reducing the tension.Speeds may seem a little high but thats no load speed so will be lower when cutting
First impressions on cutting 12mm mild stell were very good
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Old 11-06-2015, 11:44 PM   #7
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I was told by the people who make metal cutting bandsaw blades that the minimum diameter they would recommend for bi-metal blades on a bandsaw to be 14" wheels. They said that any smaller diameter than that causes premature blade failure. I have no idea as to whether or not this is so, but there seems to be about a zillion horizontal swing arm and portable bandsaws out there with much smaller wheels.---Brian
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Old 11-07-2015, 03:50 AM   #8
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the blades i use are only 6mm wide and i have also ordered a 10mm wide one
I have had a couple of bandsaws this size and have had no trouble,my previose
one had a slower speed and cut up to 6mm mild steel with no problems.The chinese hor./vert bandsaws you guys are used to use much wider blade.What surprises me how much more ummff this unit has now its geared down.Not bad for a 150w motor.I am doing a series of tests with different matls and the new saw blades,will keep you all informed.
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Old 11-07-2015, 05:47 AM   #9
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I was told by a local saw doctor that the minimum diameter of a band saw wheel should be 1000 times the blade thickness. that is for a blade .6 mm thick the wheel would be 600mm diameter. It seems excessive but admittedly he makes blades for saw mills. I saw blades there that were 3mm thick and 127mm wide. I'll keep my hands in my pockets.

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Old 11-16-2015, 12:11 PM   #10
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Just to keep you all up to speed.While making a 3 way toolpost i decided to push the bandsaw to the limit.I tried cutting a piece of 35mm thk m/s but very optimistic/hopeful.The saw cut about 3" in length before the blade lost its edge and the belt started jumping teeth.Not successful.So i retensioned the belts and fitted a new blade.I made a setsquare from 3mm thk M/S it cut quickly and easily.Then i tried 6mm plt again no problems.I also cut a piece of 5ox12 flat bar which was slow but successful.I think thats about the limit.What did surprise me was that the motor never stalled when it bogged down it was due to belt slip.


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