Resawing on a bandsaw.

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promhandicam
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Resawing on a bandsaw.

Post by promhandicam » Sun Aug 03, 2008 1:17 pm

When the specification on a band saw states that the maximum depth of cut is 230mm (for example) is it realistic to expect that the saw will be able to resaw a 200mm thick piece of timber - assuming of course the appropriate (sharp) blade is used? I'm interested in getting a band saw - primarily for the ability to resaw larger pieces of wood and don't want a nasty surprise when I can't get reasonably decent results.

Cheers,

Steve

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Post by colincott » Sun Aug 03, 2008 2:12 pm

Hi Steve

I would say yes you should be able to cut 200mm at least with it or what is the point of getting a Bandsaw so big :)

Better blades makes it easier and give a better cut ;)

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Post by opener » Sun Aug 03, 2008 2:14 pm

Yes you should be able to cut a board at the max depth of cut while the blade is sharp and well adjusted. There would only be a problem if you had large quantities to push through.

Cheers
Malcolm

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Post by ivan » Mon Aug 04, 2008 5:09 pm

A 1/2" blade will cut 200mm at a pinch but you'd find a 3/4" or wider blade better. Make sure the saw can adequately tension the wider blade. In catalogue speak "accept" does not mean "can tension for resawing".

promhandicam
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Post by promhandicam » Wed Aug 06, 2008 9:31 pm

thanks for the replies. I think it best from what has been said that I look out for a saw that will accept at least a 3/4" blade and that looks meaty enough to be able to tension it. Thanks a lot - I'll let you know how I get on in due course!

Steve

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Post by scrit » Fri Aug 08, 2008 1:40 pm

promhandicam wrote:I think it best from what has been said that I look out for a saw that will accept at least a 3/4" blade and that looks meaty enough to be able to tension it.
Hi Steve. I think I should weigh in with a few observations. Firstly when looking for a bandsaw always look for one which will take a blade 1 size wider than the maximum you want to tension. So if the maker says 3/4in, assume 1/2in, and for 1in assume 3/4in, as Ivan says. I emphasise that because welded steel frame saws all flex, even the big s*ds like this 700mm (28in wheel) machine (which is the sort of size you'll generally need to tension a 1 to 1-1/4in blade):

Image

There is a good sound technical reason for choosing 3/4in or wider for resawing and that's stiffness. Above 1/2in wide it becomes progressively less likely that a blade will bend backwards in cut (which can lead to snaking), although that can be controlled to a great extent simply by means of reducing the rate of feed. Wider blades do tend to be thicker, however, which makes then less susceptible to drift, where the blade twists slightly out of parallel with the rip fence. In any case you still need to be able to tension a blade sufficiently to avoid the blade bellying as it travels from top to bottom wheel - a classic symptom of undertensioning. You can adjust to compensate for drift, you can't compensate for bellying

All is not lost, though. Even on smaller saws there are specialist blades for resawing which do work well. Most notable is the Woodslicer blade from Highland Hardware in the USA. I've known people buy these 1/2in blades for use on small bandsaws like the Startrite 351/352 and get excellent results (these saws incidentally do about 11in under the guides despite only having a 14in wheel). The only downsides were the need to compensate for drift and the fact that the blades don't have a terribly long life. But then bandsaw blades don't last forever and they often can't be resharpened because the norm these days is for hard point carbon steel. If you're not keen on importing from the USA it might be worth looking for a blade like the Dakin-F lathers "Ripper". This is a hard point (therefore unresharpenable) hook tooth blade in low tooth count, typically 1-1/3 to 3tpi. Hook tooth blade forms cut more aggressively than the skip tooth blades which most saw doctors will try to sell you. Dakin-Flathers do not sell direct so you'll need to order through your preferred saw supplier (see Saw Doctors of Sharpening Services in Yellow Pages)

If you need longer life blades than hard points you'll need to start looking at bi-metallic blades or even carbide or stellite tipped ones. These universally come only on heavier bodies and require a heavier machine to tension properly which is why take-up hasn't been so widespread. Cost is another factor with a 180in x 1-1/14in TCT blade running around

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Post by thebloke » Fri Aug 08, 2008 2:16 pm

Scrit - at some point I would like to get hold of this bandsaw which according to the spec will take a blade of standard thickness up to 25mm wide. If I understand you correctly then I ought to look at a blade that's 3/4" wide in order to tension it correctly.
However, Axminster do a special order for all of their blades where they use 14 thou steel stock instead of the normal 20 (or 25 thou, not sure what's the standard thickness) which makes a hell of a difference on my small Euro 260 . I'm able to resaw 150mm quite easily with these thinner blades. My question is this then...suppose I were to order a 25mm wide blade for the proposed machine but made from the thinner stock, would this be satisfactory for deep resawing (300mm) or would the 3/4" standard thickness blade be better, assuming that as the 25mm blade is much thinner the machine would be able to tension it correctly? - Rob

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Post by scrit » Fri Aug 08, 2008 3:10 pm

Rob

Sorry to say but I have a problem with APTC blades - my experience of them over the years is that they are crap! Almost every one I've ever had has had big lumpy welds on it and that doesn't aid good rip sawing. They all seemed of poor quality, too, with short lives, so I would never depend on their blades (either delivery or quality).

If you want to see a good weld on a blade you need to take a look at the stuff supplied by the likes of (in mail order) Dure Edge or Dragon (last couple I had were excellent), or for that matter almost any industrial blade supplier. The downside is that higher quality in blade material and higher quality of weld will cost you more as quality is labour intensive. Personally, I have problems about moving away from established quality blade material manufacturers like Flathers because of the blade types I use. Also for ripping I have favoured a hook tooth form over the more common skip tooth form for years because they cut faster and more freely. As yet none of the established blade makers seems to do a really thin but widish hook tooth blade, so I haven't tried one. Are these APTC blades hook tooth or the more common skip tooth?

As to whether or not a 3/4in x 0.025in blade will be stiffer than a 1in x 0.014in blade the answer is I don't know. We'll need an engineer to qualify that! The 3/4in blade has a cross sectional area of 0.01875 in2 (0.015in2 for a 0.020 in thick blade) against 0.014in2 for the thinner wider blade so one would think it capable of reaching a higher beam strength. One thingh that is for sure is that the thicker blades will be better able to dissipate the heat which always builds up when deep ripping by dint of having an extra 30% of steel in them. Having resawn on 3/4in and 1-1/4in blades for a while there really isn't all that much difference in practice - as I mentioned earlier above 1/2in the problem of blade drift diminishes leaving you with just bending and bowing to cope with. The only real advantages of the wider blades are that they are slightly less susceptible to bending backwards in deep ripping, so you can cut faster, and they heat up less (for the same thickness of body that is). I now work on a cast-iron 16in machine which will tension 3/4in blades and I've had few problems not using the wider blades, apart from losing 10% or so of the feed speed.

So were I buying a new bandsaw I'd stick with my existing (good) saw supplier (Harrison's in Rossendale) and buy a machine which gives me the cutting performance I need using blades I can readily obtain. Having a rep who can pop in, is knowledgeable and helpful also goes a long way in my books

Scrit

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Post by tusses » Fri Aug 08, 2008 3:14 pm

ok - opinion wanted on my startright 352

will take a 3/4 blade and seems to resaw fine on med - high tension (ie. some left to go) is this ok ? it 'seems' ok !

ta

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Post by scrit » Fri Aug 08, 2008 5:07 pm

tusses wrote:ok - opinion wanted on my startright 352

will take a 3/4 blade and seems to resaw fine on med - high tension (ie. some left to go) is this ok ? it 'seems' ok !
Have you cut 8 to 10in high stuff on it and is it producing a flat (as opposed to a slightly cupped) surfaces? If so can you consistently saw a 1 to 1.5mm thick veneer out of it? That's the real test of your machine's blade and tensioning.

I like the little Startrites, but my feeling is that whilst they can accommodate a 3/4in blade they aren't really capable of tensioning it fully. Tests on my last Startrite indicated that even with a new tension spring it maxed out at about 12,500 psi tension (measured using a Starrett tension gauge) on a 3/4in Starrett skip tooth blade. On a 1/2in WoodSlicer it achieved 17,000psi, whilst my Agazanni 28in (700mm) bandsaw comfortably took the tension on a similar blade to over 22,000psi. Guess which could cut consistent veneers? With the 3/4in blade the 352 couldn't. With the WoodSlicer it could, albeit at a slower feed speed. Maybe a thinner saw would have performed better, but then a thinner saw would be more prone to snaking.

My current bandsaw is a 16in solid cast iron machine (i.e. the frame of the machine, not just the table) which can accommodate 3/4in blades. Cast iron is much less flexible than steel fabrications and this machine really can tension 3/4in blades to over 20,000psi and is capable of tensioning a 3/4in Lennox Trimaster III blade to almost 23,000 psi. I've yet to hear of a fabricated machine which can do that. But then this machine is more than 50 years old

Scrit

promhandicam
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Post by promhandicam » Fri Aug 08, 2008 5:29 pm

Thanks Scrit for your detailed observations - much appreciated. I currently have my eye on a used Jet JSWB 18 which I think should be up to doing what I will need with the right blades. Will keep you posted.

Steve

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Post by modernist » Fri Aug 08, 2008 6:07 pm

Scrit wrote:So were I buying a new bandsaw I'd stick with my existing (good) saw supplier (Harrison's in Rossendale) and buy a machine which gives me the cutting performance I need using blades I can readily obtain. Having a rep who can pop in, is knowledgeable and helpful also goes a long way in my books

Scrit
Just to echo that I ordered 6 odd length blades lst week from Harrisons at 15.00 and they arrived the next morning :o :o. Not bad

Brian
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Post by thebloke » Sat Aug 09, 2008 6:45 am

Scrit - many thanks for the detailed reply...much appreciated - Rob

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Post by mrgrimsdale » Sat Aug 09, 2008 8:44 am

promhandicam wrote:When the specification on a band saw states that the maximum depth of cut is 230mm (for example) is it realistic to expect that the saw will be able to resaw a 200mm thick piece of timber - assuming of course the appropriate (sharp) blade is used? I'm interested in getting a band saw - primarily for the ability to resaw larger pieces of wood and don't want a nasty surprise when I can't get reasonably decent results.

Cheers,

Steve
I've used my 352 for cutting the full nearly 10" depth on door lock-rail tenons. You can get a bit more by removing the top guide, but not a good idea.
It's not too good at this - blade gets pinched by movement of the wood, back of slot fills with sawdust and you have to keep pulling the workpiece out to stop that happening or you can't get it out at all.
So I wouldn't rate it for re-sawing at 230mm, and not too brill at 200.
There is a cheat however - do the cut as far as possible from each side, over the top of your table saw, then bandsaw out the bit left in the middle. Faster and more accurate than bandsawing alone.

cheers
Jacob
PS I do same as Scrit says - reserve new blades for ripping only, until they wander too much.

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Post by tusses » Sat Aug 09, 2008 9:24 am

mrgrimsdale wrote: There is a cheat however - do the cut as far as possible from each side, over the top of your table saw, then bandsaw out the bit left in the middle. Faster and more accurate than bandsawing alone.
I am sure if I posted that , there would be some replies ! I'll wait and see :)

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Post by robo » Sat Aug 09, 2008 8:00 pm

I recently re sawed some 10" sapele on my 352 with good results.
Blade: Hakansson Meat & Fish type 5/8" 4TPI with tension really wound up.
Dust extraction using square rain water pipe converter with blade running through.
Blades cost

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Post by scrit » Sun Aug 10, 2008 3:53 pm

tusses wrote:I am sure if I posted that , there would be some replies ! I'll wait and see :)
Yes, but the difference is that Mr. G knows about the risks involved in "deeping" whereas you're just posting because you're being a sh*t stirrer ;D

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Post by mel » Sun Aug 10, 2008 5:30 pm

Yes, but the difference is that Mr. G knows about the risks involved in "deeping" whereas you're just posting because you're being a sh*t stirrer ;D[/quote]

Dont hold back Scrit ..... Tell it like it is :o :o
;D ;D

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Post by toobyefore » Sun Aug 10, 2008 7:35 pm

Scrit wrote:
tusses wrote:I am sure if I posted that , there would be some replies ! I'll wait and see :)
Yes, but the difference is that Mr. G knows about the risks involved in "deeping" whereas you're just posting because you're being a sh*t stirrer ;D
Shame on you, Scrit.

We all know Mr G. is a sh*t stirrer too... ;)

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Post by johnnyb » Sun Aug 10, 2008 7:58 pm

On the question of tension on a bandsaw, how do you measure the tension of a blade. I look at the tension gauge on the machine, but also seeing how the blade feels.
I have a large old machine that works on a weight out the left hand side for tension, so this is set by how far out the weight is I guess on a kind of counter balance. The blade on this is 17 feet long and I mostly use an 1 1/4" rip cutting blade.
I also have a small record power tools 350s that I use for small work and I know the tension gauge is useless so I am guessing the tension.

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Post by scrit » Sun Aug 10, 2008 11:55 pm

johnnyb wrote:On the question of tension on a bandsaw, how do you measure the tension of a blade.
The only true way to do it is to use a band saw tension gauge, like the Starrett. Other than that it's a case of cranking it up until the blade no longer bows sideways in cut

Scrit

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Post by johnnyb » Mon Aug 11, 2008 8:57 pm

I can see them available in the US but any idea where to buy them over here?

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Post by scrit » Mon Aug 11, 2008 10:23 pm

johnnyb wrote:I can see them available in the US but any idea where to buy them over here?
Any engineers supply house who sells Starrett stuff should be able to help. Starrett have several manufacturing operations in the UK, most notably in Jedburgh, Scotland

I'd better warn you, though, they aren't cheap

Scrit

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Post by johnnyb » Tue Aug 12, 2008 12:56 am

Some I'd seen on the US sites are about $120 - 150. With exchange rates that could work out OK, but if that was

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Post by ivan » Fri Aug 15, 2008 6:52 pm

Re Ax bandsaw, I have the 5300 which will just about tension the max blade sized (11/4", but it is Very Difficult to fit. 1" blade no problem.

Tension Gauge:
On the 'other place' there are some posts (including 1 of mine) on home made tension gauges - use a cheap digital vernier (under 10 quid) clamped to the blade with small C clamps. Usually reccomended for deep rips, 15,000psi carbon and 25,000psi bimetal. See posts mentioned for the full SP.

Blades:
Doesn't Dragon do the 'Ripper' blade?

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Post by scrit » Fri Aug 15, 2008 7:24 pm

"Ripper" is the name used by Dakin-Flather for their narrow resaw blade, so it is bought in bulk and welded up by a lot of saw doctors

Scrit

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