how many teeth per inch?

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Re:

Postby TonyH » Mon Apr 01, 2013 3:33 pm

jrccaim wrote:Might find a specialist firm to sell you a 1.3 mm carbide drill bit. And maybe pigs will fly.


1.3 mm solid tungsten carbide drill. I don't think they stock flying pigs though.

Reading through the past posts, ToneWood was saying some blades were difficult to drill even after annealing. Who knows what steel they use these days.
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Re: how many teeth per inch?

Postby ToneWood » Mon Apr 01, 2013 8:33 pm

TonyH wrote:...Reading through the past posts, ToneWood was saying some blades were difficult to drill even after annealing. Who knows what steel they use these days.

The item description for the blade says "manufactured from quality CS80 carbon spring steel". But I was able to break the blades off the band simply by folding it with my hands.
It should be said, I've never had much luck drilling metal and my heart sinks whenever I encounter a need to do it. I usually end up breaking and/or dulling several drill bits and succeed less than 10% of the attempts. BTW I was able to get the saw blade ends orange quickly in the wood-burner by allowing them to rest under an orange glowing log - this was much faster that resting them on glowing embers for some reason.
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Re: how many teeth per inch?

Postby nic » Mon Apr 01, 2013 8:52 pm

Tony if you heat the blade up to orange and then let it cool naturally you may not soften it much, it is so thin it will cool to quickly in the air. Orange is to hot as well. You just need to get it to a red ( this is also the temperature the steel becomes non magnetic so you can check it) then let it cool slowly. Progressively moving it away from the heat source should do it. Ideally a full anneal will take 24 hours. In practice if you can let it cool till it is no longer glowing over a few minutes is should be OK. When you get to a black heat just let it cool naturally.
As to drilling it. As has been said. Centre punch, cutting fluid/ wd40 , and lots of pressure and slow speed. A drill press is much better, especially with small bits. With a cordless I often used to press as hard as I dared and just blip the trigger. You should remove swarf ( shavings) not dust. I drill high carbon steel all the time and don't own any carbide drills.
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Re: Re:

Postby jrccaim » Tue Apr 02, 2013 6:08 am

ToneWood wrote:
TonyH wrote:...Reading through the past posts, ToneWood was saying some blades were difficult to drill even after annealing. Who knows what steel they use these days.

The item description for the blade says "manufactured from quality CS80 carbon spring steel". But I was able to break the blades off the band simply by folding it with my hands.
It should be said, I've never had much luck drilling metal and my heart sinks whenever I encounter a need to do it. I usually end up breaking and/or dulling several drill bits and succeed less than 10% of the attempts. BTW I was able to get the saw blade ends orange quickly in the wood-burner by allowing them to rest under an orange glowing log - this was much faster that resting them on glowing embers for some reason.


Sure. To break a bandsaw blade I take a triangular file. I score the blade, once. One edge of the file. Put it in the vise. Align the edge of the jaws with the score mark lined up with the jaw edge. Work it back and forth a bit. Snap! Done. Do not be too fussy about scoring, although not all blades are created equal. But It is hard. Therefore it is brittle! Like glass.

When it comes to drilling, that is a horse of another colour (literally). The colour you want is blue. Said it before, say it again. Any shade of blue. Heat it until it turns blue. Enough. Orange far far too hot. You have totally annealed the blade. It has lost all resistance. It will probably break on you. You will put pins into it and put it under tension. It will almost certainly break under tension. You will curse. Why go to all that bad language? Blue that blade.
Said it before, in fact, in my previous post. Will say it again. Redundacy is redundant! But maybe I wills ave someone some trouble. When it comes to drilling your blued steel the most important thing is the center-punch, or as they say in Britain, the centre-pop. Get a centre-punch. Go to great lengths to get it smack in the centre of the blade. Do not scorn a magnifying glass; I use one routinely, well worth the expense. Put in your pop. I would really really recommend a pillar drill. Don't have one? Make yourself an alignment block, a block of steel with a hole drilled through it. This will assure a square hole. Even a wood block is better than nothing. Stick point of the drill right into the centre-pop and go to it [aside: on a pillar drill, somehow the bit finds its way into the pop] . Warning. This is metal you are drilling. The feed rates are far, far, slower than wood. And the required speeds are higher. So do not be impatient. If you have a pillar drill this will be obvious to you. You will feel it. If you are doing this with a cordless then set up a high rate of speed. But I have done this by hand, with an antique breast drill. If you have one of those, the idea is you use your chest to pressure the drill. Lean on it. Same principle as the drill press, and spin the drill as fast as you can. Be patient. This is metal, and not as easy to drill as wood.
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Re:

Postby ToneWood » Tue Apr 02, 2013 2:16 pm

jrccaim wrote:Useful hints everywhere. My own experience follows.
ToneWood wrote:[The drawback is they are not available under about 1/8 inch (3mm) - glass (or ceramic tile) drills may also work as well, and as more pointed can drill a smaller hole..;

...
Umm, you misquote me jrccaim - I didn't write that. Billman perhaps?
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Re: how many teeth per inch?

Postby ToneWood » Tue Apr 02, 2013 2:21 pm

Nic, thanks. It sounds like you've got a system that works well. I'll give that a try when my new drill bits arrive. Sounds like speed, coolant & lack of drill press might all be contributing factors to my problems.

Hi Jrrcaim,
I did try just bluing the saw blades at first but had no luck drilling them (except the two blades that finally succumbed to drilling with diamond coated grinding tips mentioned above). So I figured perhaps they hadn't been heated enough or all the way through. I hadn't intended to heat them orange - I think the wood-burner was just running much hotter the second time, as they got hot quick.
I have a good centre punch (never heard of "centre pop" before but it is spring loaded so does make a pop) and used it for all of the holes attempted - it made a pretty good impression in the blades actually, deeper than I expected.

I have a cheap Lidl drill press that I can try using (and a heavy drilling vice). Controlling the drill speed is a problem with my drill - it is a cheap £15 Focus hammer drill & and has only one speed: fast. Actually, the hammer action helps sometimes. Come to think of it, I have a couple of my father's old Bosch drills - the bigger one has a speed control but the chuck has rusted up (have been soaking it in WD40 for months but don't hold out much hope) - I considered buying a new chuck for it off ebay but I am not confident that I'd be able to get the old chuck off.

Re. Speed: jrccaim suggests high speed and Nic suggest slow speed - which is better?
High-speed has not worked very well for me so far but perhaps other factors are at play. Slow speed vaguely sounds right to me, perhaps recalling metal work classes long, long ago at school. Is "work hardening" an issue with high-speed drilling metal. Just found this: http://store.curiousinventor.com/guides/drill_speed/ & this: http://www.doityourself.com/forum/weldi ... steel.html )
Looks like its a trade-off but sounds like slow would be more appropriate for me (hobbyist who trashes drill-bits).
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Re: how many teeth per inch?

Postby nic » Tue Apr 02, 2013 2:35 pm

The link to drill speeds looks good to me, if you go too slow it will just take a bit longer, go to fast and it you will melt stuff. Bear in mind though that you need a higher speed for smaller bits. Annealling, or my quick version of it won't make the steel that soft so I wouldn't worry about that. The steel I am using at the moment will kill drills and files if just taken to briefly to Blue.
If the drill is too fast just blip the trigger, it will stop stuff overheating. Hammer action will kill a small bit, if you need it something is wrong.
If you have a drill press, however pathetic it looks, use it!
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Re: Re:

Postby TonyH » Tue Apr 02, 2013 2:49 pm

I hope posting links to other fora isn't going to upset anyone, but some useful discussion here on UK Workshop about how to replate a tenon saw
HERE.

In summary, drilling saw plate is not easy, punching is easier. If drilling I would go with nic and go slow - going fast can just overheat cutting edges of the drill. Another point alluded to in the thread is to use a HARD backing block to drill through into mild steel may be better than wood - as well as making for a neater hole, a thin springy sheet material under a lot of pressure from the drill tip will deform.
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Re: how many teeth per inch?

Postby gavin » Tue Apr 02, 2013 5:22 pm

ToneWood wrote:I did try just bluing the saw blades at first but had no luck drilling them (except the two blades that finally succumbed to drilling with diamond coated grinding tips mentioned above). So I figured perhaps they hadn't been heated enough or all the way through. I hadn't intended to heat them orange

Heating in a domestic gas ring works well, or on a propane torch. Polish a section and watch the colours run across the polish . When you see blue remove from heat.
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Re: how many teeth per inch?

Postby ToneWood » Fri Apr 05, 2013 6:45 pm

Well, I finally managed to finish drilling all of the holes - but it cost me 2.5 new 2mm drill bits: 1 new cobalt drill bit and 2 cheaper new HSS drill bits.

I took Nic's advice and used my cheapo Lidl drill-press - after some adjustments it actually worked quite well and I will likely use it again :)
I also used WD-40 as coolant/lube.

I used the cobalt drill tip first, with pulses on the drill trigger to keep the speed down. It worked well, producing shaving as Nic described.
However, when I tried repeating this on the second hole the bit promptly snapped off (brittle?). (The seller has kindly offered to replace it.)

Fortunately, I had a feeling this might happen, so as a back-up, I bought a cheap pack of cheap 10x2mm ToolZone drill-bits this morning (the store had sold out of 2mm cobalt bits - but I recalled Sean saying that he just used regular HSS bits without problem). The HSS bit didn't seemed to work at first but a burst of high speed caused it to produce some smoke, dust and another hole :)
However, when I tried repeating this on the second hole the bit promptly snapped off - again :(

What finally worked:
Anyway, I ended drilling another 3 or 4 holes without further breakages using:
- a regular HSS bit,
- full drill speed (only a single relatively short burst is need) when
- moderately firm drill press pressure is applied
- WD40 as coolant/lube
It produced metal dust & some smoke/heat, rather than nice shavings, but it worked. I suspect the final drill bit is blunt now - but, who knows, it might manage another hole or two.
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Re: how many teeth per inch?

Postby ToneWood » Fri Apr 19, 2013 7:08 pm

I got another bow saw, the little one below, with London handles. Previously I would have worried that finding blades for this unusual size might be difficult or impossible but not any more (thanks guys) :)
Bow saws 3.jpg
12"- 10"- 7"
Bow saws 3.jpg (115.28 KiB) Viewed 8879 times

BTW I've inserted the blade into my 12" to cut on the pull stroke - it was an idea I had been toying with for a while. The new blade is thinner & less stiff than the previous one and it seemed like setting it up to cut on the pull, rather than the push stroke, might help - and it does, it works brilliantly :). Much easier and more controlled, less jerky. Having a sharp, slim, new 10TPI blade which cuts really nice and smoothly too, doesn't do any harm either :). I read something last week that suggests that this was actually quite common practice in the past, which is reassuring.
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Re: how many teeth per inch?

Postby jrccaim » Sat Apr 20, 2013 5:04 am

ToneWood wrote:Well, I finally managed to finish drilling all of the holes - but it cost me 2.5 new 2mm drill bits: 1 new cobalt drill bit and 2 cheaper new HSS drill bits.


Paradoxically the better (i.e. expensive) the bandsaw blade the harder it is to drill it. I try to get plain old steel blades. They are much easier to blue. This is because the really expensive bandsaw blades have Chromium, Vanadium, and who knows what other members of the periodic table in them. That is because they are made for extended use by people who will never, ever, sharpen a bandsaw blade, and furthermore they will use them at high speeds in a powered bandsaw. So they are made to last as long as possible under this stress. We will never do this in a bowsaw! Not even Superman can move a bowsaw fast enough to cause heating. So plain old steel blades are quite good enough. To drill, I use TIN coated asiatic drill bits. I have drilled quite a number of saw blades by now. Advice. If the surface color is blue, and it is a fancy blade (Chrome-Vanadium-Osmium-Iridium, name your elements, and you don't know which pieces of the periodic table they added) and it resists drilling, then heat it some more. You might have to go to a very dark blue indeed. It is the steel that is turning blue, but the Osmium... etc. is being stubborn. As it should, that's why they added it! Whatever you do (a) center-punch it first (centre-pop in Real English) (b) use a very light feed on the pillar drill. It is a completely different feel (from wood) to drill metal. Even in plain old steel I would not even attempt to drill bandsaw blades without a pillar drill. You cannot feed a hand drill as accurately as in a pillar drill. Nor can you keep it square.

OK. you have a pillar drill. But if you dulled the bit you went too fast on the feed. Enough, MacDuff. Don't feed so fast. But also see below.

There is yet another factor in drilling metal. The speed of the pillar drill. What really matters is surface speed. That is, speed at which the edge of the bit moves in meters/sec or any other unit. The drill speeds are usually pulley-adjustable. In RPM of course. When we are drilling bandsaw blades with small bits we want full speed, because we are drilling very small holes (2 mm or less) and the radius is small, so the surface speed is small (factor of two pi of course). So set the pillar drill to max speed. All pillar drills of my aquaintance acquaintance have pulleys that allow you to do this. Usually there is a handy table inside the cover that tells you what the RPM will be; pick the largest. Crank speed up to the max RPM. Is a pain in the a*** but well worth the trouble.
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Re: how many teeth per inch?

Postby ToneWood » Mon Apr 22, 2013 1:26 pm

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Re: how many teeth per inch?

Postby Shankar » Tue May 07, 2013 7:25 am

Recently bought a 12 inch turning saw off e-bay for 14 quid inc. p&p, lovely condition but the blade was rusted and somewhat blunt.
I've got a replacement which has teeth going to the ends so obviously cut from band saw blade and is 9 mm deep, 11 TPI. The old blade looks original and is 6 mm deep, 10 TPI. I assume the thinner blade will allow tighter cuts.

1) Should I try to sharpen ( inexperienced- what file will I need) or will sharpening be a hiding for nothing (except the experience of course :) ?

2) How do I know when the blade tension is high enough ?

Thanks
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Re: how many teeth per inch?

Postby gavin » Tue May 07, 2013 8:40 am

Shankar wrote:1) Should I try to sharpen ( inexperienced- what file will I need) or will sharpening be a hiding for nothing (except the experience of course :) ?

The purist answer: You should always try to sharpen everything. You'll learn more that way. You'll need a small triangular file. If the gullets you file are say 5 mm deep, your file should be ideally either 5 or 10 mm filing faces. Any other sizes and you'll have file teeth worn to differing amounts. There's plenty of on-line resources about filing.

The practical answer: At a guess your blade will be so narrow ( it is a turning saw ) that you will not be able to anchor the blade in any sort of saw vise for filing.

So I would actually suggest you buy a blade. Or try any old broken bandsaw blade from a joiner's shop. What they discard for high speed work may work for you. Cut to length. Heat the last 20 mm of each end of the blade to cherry red. Let cool. Drill holes in each end of the blade to match your frame. It is really easy.

Shankar wrote:2) How do I know when the blade tension is high enough ?

It will cut work, but not break the frame. Try incrementally tightening 2 extra turns at a time, test and repeat tightening if need be.
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