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Bandsaw speed

How can I slow it down

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Plasma01/05/2019 19:07:03
337 forum posts
41 photos

Hi all,

I have a small bandsaw which is direct drive from the motor, it's fine for cutting wood but I would like to use a metal blade in it for cutting brass.

I think it needs slowing down but have no idea how to achieve this by electrical means.

Does anyone have any suggestions as to how to go about making, fitting a speed controller or if it would be possible.

As an aside I have some 3/16th wide bandsaw coil 32 tpi wavy or rake set if anyone needs some.

Photo of motor plate below.20190501_183319.jpg

Regards Mick

duncan webster01/05/2019 19:15:12
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2232 forum posts
32 photos

From the motor plate I reckon that is a single phase capacitor start motor, so speed control is a non starter. Either ft a 3 phase motor, or arrange a counter-shaft to drop the speed (not all that easy I suspect).

Ian Parkin01/05/2019 19:15:55
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655 forum posts
174 photos

Is it a Inca saw?

I use my Inca for cutting non ferrous materials with no adjustments

You cant really speed control that motor

replace motor with 3 phase or bring the motor off and use pulleys to slow it down if you think you need to

JasonB01/05/2019 19:37:59
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I use my old Rexon for non ferrous at the standard wood speed, cuts ok if a bit noisy. Will go through 3" ali OK and have done 1" bronze.

Simon Williams 301/05/2019 19:39:14
412 forum posts
67 photos

Let's do a bit of arithmetic.

I've got a bandsaw I bought second hand recently, I've been musing on the same question. For my bandsaw a motor of approximately the same speed and power also drives the blade directly. For the sake of a worked example I'll use the dimensions I took from my saw.

Drive wheel is 1 foot in diameter, and runs at 985 RPM. So linear speed of blade is 1 x 3.14 x 985 ft/min = 3000 ft/min in round numbers.

Recommended speed to cut mild steel with high speed steel blade is approx. 100 ft/min. That's a speed turn down well beyond the range of any variable frequency drive three phase or otherwise. Not to mention the problems of keeping the motor cool.

I pretty sure (though I don't know how to quantify it) that the torque requirement to cut steel will go up from that needed to cut wood. So we're into some pretty significant gearing here. I've been musing on whether to make a planetary gear reduction along the lines of the Dore Westbury mill, but it's a lot of work and it's never going to happen.

Having said that, Stefan Gotteswinter says he cuts steel on an ordinary (vertical) bandsaw, but it's not clear what speed the blade is running at. Have a look at the YouTube video of his basement workshop walk-around.

An HSS blade is going to cost £20 or thereabouts a kick, my feeling is that the teeth will come straight off it as soon as you show it a piece of steel. Cutting ally or possibly brass will probably be OK, though the cutting speed is still far too high.

So I decided that a bandsaw designed for cutting wood wasn't a good place to start.

HTH Simon

 

edit - Jason (as ever) beat me too it.

Edited By Simon Williams 3 on 01/05/2019 19:40:51

Plasma01/05/2019 20:02:57
337 forum posts
41 photos

Yes it's an Inca saw. The 32 tpi blade cuts brass no problem but seems to load up when cutting aluminium.

May need a coarser blade I guess.

I have a pair of bandsaw wheels so could have a crack at making a steel cutting saw.

Mick

JasonB01/05/2019 20:10:29
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Simon, not sure where you get your steel cutting speeds from but my Femi metal cutting bandsaw has two speeds - 60 or 80m/min which is a fair bit more than 100f/min

Martin of Wick01/05/2019 20:47:42
93 forum posts
4 photos

Depends on blade, teeth count, how robust and solid everything else is etc. My CY90 (budget class small horizontal band saw not that solidly build but performs well within its class) speeds are 20/30/50 m/min.

using 14tpi carbon steel blade at 20m/s it is quite comfortable with steels, but certainly not at 30m/s

Aluminium and brass fine at 30m/s, or lower, any higher it starts skipping and grabbing, so I have never use the high speed but expect it would be fine for plastics

Martin

martin perman01/05/2019 21:13:15
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1657 forum posts
67 photos
Posted by Plasma on 01/05/2019 20:02:57:

Yes it's an Inca saw. The 32 tpi blade cuts brass no problem but seems to load up when cutting aluminium.

May need a coarser blade I guess.

I have a pair of bandsaw wheels so could have a crack at making a steel cutting saw.

Mick

Plasma,

Get your local saw doctor to make you a skip tooth blade, take your current one to him for the length and tell him what your trying to do and he should give you the correct tpi and skip tooth.

Martin P

Edited By martin perman on 01/05/2019 21:13:51

Plasma01/05/2019 21:26:16
337 forum posts
41 photos

As an add on, does anyone have any experience of brazing or silver soldering bandsaw blades rather than welding?

Just wondering if there is a preferred method of joining bandsaw coil without using a blade welder.

Martin not sure that I have a saw doctor, those kind of skills seem to have been lost.

Mick

ChrisB01/05/2019 21:44:05
400 forum posts
162 photos

I run a 1/2" 8/12 tpi vari-tooth blade on my Nebes tm101, is variable speed from 30 to 80m/min but most of the time it's set at 80m/min and I have cut both steel and aluminium without any issues. With higher tpi you'll get a better finish but it will take longer and probably load the blade with softer materials, I found the 8/12 vari-tooth works much better to the 14tpi the bandsaw came with.

As for welding a blade, I managed to weld one with a tig welder - acceptable, ie it didn't break again but I needed to grind a bit to remove excess material.

oldvelo01/05/2019 22:08:10
156 forum posts
43 photos

Hi Plasma

You will need to slow down the band speed with a counter shaft or gear box. May I suggest you use Poly Vee Belts 6 ribs will be more than adequate for the existing motor. Pulleys are easily fabricated and capable of quite large ratios.

Use an idler pulley on the back of the belt to give the small drive pulleys to give a better contact area.

More can be seen in my album Bandsaw 2.

Eric

pgk pgk01/05/2019 22:30:59
1454 forum posts
282 photos
Posted by Plasma on 01/05/2019 21:26:16:

As an add on, does anyone have any experience of brazing or silver soldering bandsaw blades rather than welding?

Just wondering if there is a preferred method of joining bandsaw coil without using a blade welder.

Martin not sure that I have a saw doctor, those kind of skills seem to have been lost.

Mick

If memory serves 'Tom's Techniques' did a youtube vid on silver soldering bandsaw blades

pgk

Bruce Newman01/05/2019 22:40:52
8 forum posts
2 photos

Hello Plasma

To join a bandsaw blade, make blade about 3/4" longer than finished length, grind a chamfer about 3/8" long on each end so that when they overlap the blade is the right length.

Make a jig from a length of steel, 1" square will do, cut a recess across in the middle about 1" long x 1/2" deep. drill and tap a couple of screw holes each side of gap so that the blade can be clamped down by screws with washers.

Carefully line up blade ends across gap, chamfer to chamfer so the ends are in close contact, tighten screws, then flux and braze or silver solder. If joint ok clean up on grinder if needed to correct width so it runs smoothly.

Cheers

Bruce

Derek Lane01/05/2019 22:41:05
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206 forum posts
49 photos
Posted by Plasma on 01/05/2019 21:26:16:

As an add on, does anyone have any experience of brazing or silver soldering bandsaw blades rather than welding?

Just wondering if there is a preferred method of joining bandsaw coil without using a blade welder.

Martin not sure that I have a saw doctor, those kind of skills seem to have been lost.

Mick

This GUY makes blades to suit many needs I use him for all my bandsaw blades.

IanT01/05/2019 23:27:46
1325 forum posts
136 photos

I use Tuffsaw too Derek - good quality, reasonable prices and great (e.g. fast) service.

I've purchased a range of bandsaw blades (various widths & tooth ratios) from him for my INCA bandsaw - but no way am I going to try cutting metal with it. It might well cut non-ferrous but so might SWMBO's bread knife given enough welly.

The INCA was designed to cut wood and it does so very well. I'm not about to risk 'naggering' one of my favourite wood working machines by trying to make it do something it was never intended for. If you want to cut metal Plasma - then get a saw designed to do so....there's quite a wide choice of them available.

Regards,

IanT

JasonB02/05/2019 07:01:21
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Posted by IanT on 01/05/2019 23:27:46:

then get a saw designed to do so....there's quite a wide choice of them available.

This does raise the question of what sort of cutting Plasma wants to do.

There is a limited choice of vertical metal cutting bandsaws which are best for sheet where the deeper throat is the main advantage. If it is for cutting section to length then a horizontal will be better and you do have more choice at the lower price end of the market.

Now I have the Femi my old Rexon only gets used for the odd bit of sheet/plate that won't fit the Horizontal.

I also use 8-12 vari-pitch M42 in the Femi , the old woodworking saw uses up blades that are past their best for wood so mostly 10 or 12tpi for section, less for sheet/plate.

Edited By JasonB on 02/05/2019 07:01:53

Bruce Newman02/05/2019 08:10:23
8 forum posts
2 photos

Whoops! I made an error on joining bandsaw blades, should say: make blade 3/8" longer and not 3/4". Schoolboy error.

Bruce

martin perman02/05/2019 08:22:40
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1657 forum posts
67 photos

Here are a couple of pictures of a vertical bandsaw I recently moved on to a new home, the previous owner had modified it to slow it down. Sorry about the pictures, they are upright on my laptop.

Martin P

img_7232.jpg

img_7230.jpg

Mick Henshall02/05/2019 09:47:59
519 forum posts
29 photos

A floor polisher/ buffer has a output rpm of about 325 ( via two gears ) with 1 ft bandsaw wheel gives around 1020 ft per min, a 2" pulley on motor driving a 8" on countershaft gives 255 rpm, a countershaft pulley of 2" driving 4"on bandsaw gives about 127 rpm. My maths are suspect but 130 ft per min should be ok, find an old buffer. I used a buffer motor to drive a prototype home built shaper with success

Mick 🇬🇧

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