fine rigid saw needed....

[jonboy]

Problem:
I have to saw a 325 x 240 mm... 13inch x 10 more or less mahogany panel , 5mm thick (touch less than quarter inch) into two sheets.... I have done this before on mm or so thicker panels so I am not asking for the 'how' so much as the source of a saw .... I make up a steel framed jig so the saw can't wander through the thickness of the panel... and
I have done this on much bigger panels, but never on a such thin one as this...
Facts : The finest hardpoint saw I can find with a suitable length is a Sandvik 15 tooth to inch with a useable stroke of max 12"
Even this blade at tooth width of 1.5 mm (sorry guys I have to go metric from here ) gives a cut of closer to 2 mm. Finer toothed saws are usually too short.. little fine craft saws have blades only 150-200 mm max long and are not up to cutting for a couple of hours effectively through a one square foot block of mahogany (ok its only 5mm thick but the saw doesn't know that....)..The rigidity of the blade is critical so I don't think I can go down the fretsaw- cable saw route and fine jewellers blades only come three or four inches long....and I I must have total control so power tools are out...
in short, I need the finest toothed, slimmest bladed saw with a blade depth of 2 or 3 inches 75 mm or so, and a stroke length of at least a foot, I can buy... I tried a funky Japanese number once but it cut on the back stroke and actually wasn't really any better than the hardpoint mentioned above and ten times the price, ......
Any ideas , addresses, gratefully received, happy to provide more info or discuss further as necessary...J

[Torna]

If I really wanted to do this by hand I would try
1) Take an old handsaw, grind off the teeth, and file some new teeth at whatever pitch & set I wanted. OR
2) Take an old handsaw, and braze a piece of fine-pitch bandsaw blade onto it. OR
3) Use a piece of bandsaw blade in a bowsaw.

-leif

[Milo Christensen]

You're describing a perfect job for a surgically sharp, absolutely flat blade on the outside, teeth kerfed on the inside Japanese backsaw. The pulled blade is completely ridgid and perfectly controllable. The fact that it's being pulled makes it possible for the blade to be the narrowest blade you're going to find for this job.

If you've a jig to control blade wander, even better. The end result is a book match cut, right?

Edit/update: So I went down and put a micrometer on mine. 0.6 mm.

[ishmael]

I'm not quite seeing this. You're worried about how much stock is there? A well wielded skill saw only takes about twice the kerf of a dozuki. A hell of a lot more friendly in plywood.

[S B]

I would cut that with a utility knife,multiple passes,held flat against a piece of angle iron. Change the blade between strokes,if it started to jamb.

[andrewe]

S.B., He is cutting it like separating two sheets of paper. I am with Milo, a Japanese saw supported at each end on a flat table, cutting sideways. Possibly with another support for the handle, to ensure a linear pull.
A

[S B]

S.B., He is cutting it like separating two sheets of paper. I am with Milo, a Japanese saw supported at each end on a flat table, cutting sideways. Possibly with another support for the handle, to ensure a linear pull.
A
I wasn't paying enough attention. You can purchase blades, about20"X 1 1/2" fine tooth, for a miter saw Can Tire sells. I realize that is no good for you, but there may be something similar in your area. Most machine shops have all sortsof gear, not suited for sale to the general public.The other option, if you don't need both sides of the panel, is to run them through a thickness planer. On the other hand if you have a Rembrandt painted on either side and need to save them both?

[jonboy]

Ok it's not a Rembrandt but you have it; both sides are to be saved ...I have done this several times before ... I hope you follow this. I make two frames from say 19mm angle, the size of the panel...flush fitting inside each frame is a piece of 17mm ply or melamine faced chip board so I have made two 2mm deep trays..... when the panel is clamped between the two, there's a 1mm gap, with 2mm of the panel each side 'in ' the box. When the saw passes through the gap it can't wander, and there are various ways to stop the box closing behind the saw, guiding the blade for the first couple of cm...and so on .... as I said, the method isn't the problem.
I haven't done this on such a thin panel this size, and the thinnest saw blade I can find makes 1.5 mm cut and isn't long enough to pass back and forward through the job.

The mitre saw blades SB aren't thin enough, and one option I used on a job like this before was to braze two saws nose to nose, which worked, sort of, but the brazing took the temper out of the teeth and imagine a butt joint held only by a whisker of brass....it worked only because the steel blade was thicker..

So, if I can find a blade that makes a cut of 1mm, absolute max 1.5, and is at least 35cm ,14" long, doesn't have a backbone like a tenon saw....The client gets two 1.5mm panels and has doubled his money...I get a cheque, a few more grey hairs, and a pile of superfine mahogany sawdust.
BUT I CAN'T FIND A BLEEDIN' SAW......

[P.I. Stazzer-Newt]

Bandsaws come on 500 foot rolls - huge choice of toothform, blade depth and kerf width available, and relatively cheaply.

I knew a man who used a home made wood framed tensioned saw with bandsaw as the cutting part to make the book-match cuts for 'cello backs.

[jonboy]

Bandsaws come on 500 foot rolls - huge choice of toothform, blade depth and kerf width available, and relatively cheaply.

I knew a man who used a home made wood framed tensioned saw with bandsaw as the cutting part to make the book-match cuts for 'cello backs.



Sounds on the right track and thanks Milo too ....Any specifics ?? Mail order suppliers, names and addresses..websites.....doesn't matter where....

[andrewe]

www.axminster.co.uk (http://www.axminster.co.uk) sell lots of bandsaw blades. And undividual, not 500ft if small bits needed. Stuff arrives here in a couple of days.
A

[jonboy]

Thanks Andrewe... that axminster site alone looks like the answer, and now I know what genre I am looking for, (never even knew about flush cut saws) and the reason for my lack of success with a Japanese saw before was I realise now not the saw's fault...
Thanks everyone for your attention and don't think the thread closed if there's still more to come.....

[P.I. Stazzer-Newt]

Speak to These Folks (http://www.starrett.co.uk/contact/) - phone email or whatever...

[Bob Smalser]

Problem:

I have to saw a 325 x 240 mm... 13inch x 10 more or less mahogany panel , 5mm thick (touch less than quarter inch) into two sheets....

....I have done this before on mm or so thicker panels so I am not asking for the 'how' so much as the source of a saw .... I make up a steel framed jig so the saw can't wander through the thickness of the panel... and

....I have done this on much bigger panels, but never on a such thin one as this...


Are you trying to resaw this panel into two identical sheets of leaves so you can, for example, bookmatch it?

A panel 10 inches wide and only 5mm thick?

Sorry, but if so, none of anything yet mentioned will work very well, especially if you intend to plane or sand the sawn surface clean. You'll only succeed in destroying it. Make another panel.

[jonboy]

That's a couple of times now... I don't understand what 'bookmatch it' means... but yes.

don't worry about the whys and hows guys, just keep coming with info on fine tooth thin blade saws...phew been online all afternoon and still haven't found a blade long enough...The jap ones are getting there super-fine, super- thin blades but still a couple of inches shorter than ideal...

Custom saw maker anyone??

[Bob Smalser]

This cabinet door panel is bookmatched. The panel stock sliced through and through, opened up like the leaves of a book, edgejoined, planed and sanded. It's a simple technique to turn a plain board into something special.

http://pic20.picturetrail.com/VOL12/1104763/2594265/38401087.jpg

http://pic20.picturetrail.com/VOL12/1104763/2594265/38474568.jpg

I've made several resaws over the decades, but never one capable of slicing 1/4" X 10" stock. You need a wide rip blade that cuts by chisel rather than shearing effect only with less rake than a typical rip saw. You can make one from a wide bandsaw blade if you file out any hook in the teeth and ease the rake. The one on top is a large resaw:

http://pic20.picturetrail.com/VOL12/1104763/2594266/300720196.jpg

But by all means make yourself a frame saw and try these things for yourself. I suggest you log on here and search their hand tool forum for current sources of blades. You'll find lots of enthusiasm there.

http://www.sawmillcreek.org/

[andrewe]

Thanks P.I, I have used Starrett for years. Think 100X 50mm holes in 6mm SS bar for one job. But never had the 'nouse' to look at the web site.
Jonboy, Bob S really knows what he is talking about, so pay attention. (if you didn't know already)
I am fascinated about what panels warrant the effort to split them. If not Rembrandt, any other artists we might recognise?
A

[kc8pql]

The real answer to your problem is a well tuned bandsaw, with a sharp, 1/2", 6 tpi hook or skip tooth blade and a high fence. The kerf will be about 1/16" wide, maybe a touch more. I've cut 1/16th" thick veneer that way on my old Powermatic 20" saw. Splitting a 1/4" panel is quite possable. Find a shop with a good heavy saw and pay them to do it.
All this assumes that your panel is dead flat and even moisture content all the way through. If not, your screwed anyway.

[jonboy]

Thanks P.I, I have used Starrett for years. Think 100X 50mm holes in 6mm SS bar for one job. But never had the 'nouse' to look at the web site.
Jonboy, Bob S really knows what he is talking about, so pay attention. (if you didn't know already)
I am fascinated about what panels warrant the effort to split them. If not Rembrandt, any other artists we might recognise?
A
Probably not, unless you are familiar with the Portuguse 20th C art market in this case...just to say the sum of two paintings by this artist is considerably more than the cost of splitting the panel and much more than a panel with a painting on both sides.. As I said, I have done this before a few times , from an Italian mediaeval double sided oak tryptych altar piece panel to a hardboard 1950's bit of contemporary but seriously valuable crap , in my humble opinion, (but I am a conservator not a dealer), and the market dictates...

can't make sense of the Starret site though, seems to be analytical optical gear... enlighten me...??

[P.I. Stazzer-Newt]

....
can't make sense of the Starret site though, seems to be analytical optical gear... enlighten me...??

They make a very large range of different band saw blades.

http://www.starrett.co.uk/products/sawblades/bandsaw/

It might be wise to side step the usual wood cutting blade forms for something like the Versatix MP M42 range - but since the requirement is rather special - talk to an expert.

Most people doing re-saw or veneer cutting can afford a considerable scrap rate - I'd not want to be on the steep part of the learning curve for the job you describe.

[Bob Smalser]

...just to say the sum of two paintings by this artist is considerably more than the cost of splitting the panel and much more than a panel with a painting on both sides...

... I am a conservator not a dealer....



I didn't realize we're talking serious money and risk.

Take it to a couple professional shops for an estimate. I've worked in four or five good ones, albeit with old iron, and on the best bandsaws wouldn't give you anywhere near a 100% chance of success resawing a 5mm panel that wide and cleaning the resulting sawmarks. David G. here has an architectural millwork shop and will have a better appreciation of more modern machines.

There are few absolutes. Blades track differently resawing different woods. The good news is that most mahoganies are even textured. You can use a damp sponge to control any cupping. I'd mock up a couple identical mahogany panels to play with, but suspect I'd end up stoning the blade set to track in the mock panel and still use a point fence and steady hand rather than a fixed fence with a higher dependence on the blade set alone preventing runout.

[2MeterTroll]

IIRC is that they make a band saw that is flat for this sort of resawing. the blade is horizintle above the table and adjustable. the feed rate is very slow and the blades are very wide so they dont tend to wander.

for the life of me i cannot remember what the name of the saw is.

I think that if you have a band saw it would not be very hard to make a adjustable structure for it that will either move the saw through the stock or the stock through the saw.

[Robert W. Long]

This guy can resaw your panel. No doubt about it. I resaw for a living and he can do it much better than me.
http://www.borsonresaw.com/

[Milo Christensen]

Jonboy: don't get too hung up on the length of the saw blade. You're going to cut this by hand, in a jig. So: cut in from each corner at a 45 degree angle until you can't effectively saw any more. Then from each side, cut off the diamond shape that's left in the middle. I wouldn't think you're going to be sanding the backs, are you?

[S B]

This is an interesting problem, it crossed my mind at work today and I took out the saw and measured it. 21 1/2" long, 1 3/4"wide and about 1/32 " thick. Kerf 3/64" or fat 1mm. Actual saw is no good,throat4 1/2", but the blade is about as skinny as wood saws get. 16 points per inch, cuts in only one direction but agressive. Google Canadian tire, the miter saw is a hobby tool, but the blades are nice. If you can't get one, I'll send you mine.

[jonboy]

RWL ...good site, but can't go down that road... can't have lubricants, must do it myself...really can't risk power.... I can hand saw one pass, open the jig and take a peek if I have to.....California's a way away....tempting though! thanks
Milo the cutting in from corners is a last resort.... I did it once on a 4mm thick cardboard sheet painted both sides, same jig principle as mentioned and with a serrated 15" ham knife...with the best results on test pieces still giving a step where the corners and diamond met....lots of back clean-up and other minor probs... might well be the way to go, if all else fails..
And SB... thanks for the offer v. considerate....I have used the mitre blade set up in an adapted frame to give a deep throat, if you pardon the expression, but I too just miked my blade and did a couple of passes into a lump of hardwood and am getting a 2mm cut...might find a thinner blade though...
I think the answer if I can't get a firm like Starret to even make me a one - off, is to a get two jap saws, typically with about a 10" blade length and get a professional to butt weld them nose to nose, or at least one behind the other to maintain cutting direction, and grind and clean up the join...If there's a cm or two at the joint with no teeth even, I think it will work...
When I did this before it did work, and I am from the point, shut my eyes and splatter school of welding... with the right clamps and heat sinks I think this will be the answer....Still looking for a shop-bought long enough blade....for a day or two more at least ... Keep ya posted, maybe some photos if I can figure out how... regards, J

[2MeterTroll]

actually if your going to do it by hand go find a saw sharpener (the person) take a 1" wide band saw blade section the length you want have him hollow grind it and put a cleaning tooth about every 1/2" and some variable teeth between. them take that blad back to the shop and build yourself a frame that can take the tension you will need for the blade to remain tight. or you could find someone with a laser cutter.

[MiddleAgesMan]

As I understand it the solid mahogany panel is painted (sealed) on both sides. As it sits today it is balanced. Once you split it (assuming you find a way to do it) you will have two unbalanced panels.

Wood less than 2mm thick can be prevented from warping through mechanical means but, assuming the resawing is successful I think it imperative to immediately seal the raw backs, preferably with similar material(s) as was used for the faces.

[jonboy]

The traditional method, that I use, is to make cradle for the back of each panel...a lattice of half-housed fillets about 5mm x 15mm , five or six in each direction on this sized job... or simpler, glue the two panels onto new ones with a wax -resin glue and my vacuum hot table... Standard practice for relining old canvas oil paintings onto new canvas..... they are paintings, going into frames so thickness not an issue within reason..


" What's the difference between a duck ? one of them's both the same"

[S B]

The cut measurement I gave you was from a cross cut in spruce. I have never had the need to slice a piece of wood that thin, but it presented an interesting problem. Not having been shown the standard method, this is how I imagined I would proceed. Cutting accurately through a piece of 6" wide timber is nothing to write home about, so if I laminated blocks, same size as the panel,but 3" thick, and clamped one to either side, I should have a simple job. With angleiron clamped in place to start each edge and after cutting about 1" deep, I would cut from the corners allowing the saw to follow the already established path. With the iron removed it should be a simple task to keep the saw straight. Any pics of your gig?

[jonboy]

You have it SB, essentially what I say in Post#8 above, though from previous experience it isn't easy to keep the saw on track if I don't guide it by the angleiron frame. The frame also ensures the whole jig stays true...as its so easy to distort the whole thing by clamping it in the bench vice for instance..also the iron frame can only guide the blade if each end of the saw stays outside the jig at the start and end of each stroke.....
couple of developments.......by using 25mm thick perspex as my boards I can watch what's going on;
and a 'durrr' moment with the mitre saw...turn the blade through 90º and hey presto no throat depth problem...had to mess about with the tensioner and blade anchors.....
I have just bought a selection of Jap saw blades to experiment with, including flush cut blades with no set,..What I guess Milo was talking about in post#3 ..as one problem I have had is, as the saw will inevitably rub against the sides of the iron frame, I get dull blades in no time...three or four hardpoint saws in the bin for the last job this size....but the flush-cuts only come up to 150mm 6" so I have to join at least two, as above...
Keep it coming lads and lasses.

[S B]

This might be over kill, but ripping a few pieces of thinner material, like door skin, would boost the old confidence before sticking the saw into the expensive stuff. Coating the frame with plastic or wood will reduce the abrasion on the saw,it's path is guided by the blade not the teeth.