[OP]
Member
I just took several handsaws to a local handsaw sharpening shop here in central PA. We had a discussion about the fact that the teeth on some saws seem to get very hard and brittle, ruining files and possibly breaking off if you try to re-set them. He seemed to think my saws may be OK, but I have run into this problem in the past.
Is there any way to correct this problem on such older saws? These saws are older Diston, along with one Fulton backsaw.
Member
some saws are made to not be re sharpenable,but I don';t know how far back this goes.
The only cure for hard teeth would be to heat them to a spring blue color. But,without special ovens,this might be impossible without warping the blades and ruining them.
If it was do or die,I'd take a narrow grinding wheel and rig up a jig to hold the saw at the correct angles and grind the teeth. But that would be very complex,and still no way to SET the teeth.
Contributor
Howdy William and welcome to the Creek. Without a location in your profile old fogies like me will likely forget your are in Central PA.
There have been a couple of discussions here about some, mostly older, saws having varying hardness to the point of being very hard on files.
I have no source to verify this, but sometimes I think pitting on the plate can also play into this problem of teeth snapping off when setting.
It is possible to find honing stones in different abrasive material. I have had success using an India stone on bandsaw teeth. It is slow and tedious, but with the difficulty in finding decent saw files these days it might be an option to try. Not sure a saw sharpener for hire would want to do this.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
[OP]
Member
Updated my profile.
Yes, the saws, except the backsaw, have some rust, no major pitting near the teeth. Many of my saws (and other tools) went through a flood years ago, somehow the handsaws were overlooked for a couple days before I got them washed and dried. I was heartbroken.
Heating in an oven: George, I do seem to recall while looking for pertinent threads on this your discussing temps you would need to reach to bring the blades up to spring blue, I think you were looking for 650 - 750 deg?
I'm wondering if this could be done in a regular oven if I use a remote thermometer.
Local handsaw sharpening services are becoming more limited in this area as the old-timers retire or pass away.
This guy is Amish and has a sharpening business that serves a wide area, and I am pretty sure will be using a Grizzly narrow belt sanding rig to sharpen the teeth. He did seem to know his way around handsaws, but I am pretty sure trying to change the temper in the blades is a mystery to him. So until next Thursday I am keeping my fingers crossed and am anxiously waiting to see the results for myself. His electric tools are driven from a generator powering a motor driving a belt shaft for all his rotary tools. Typical for this area. I asked him if he would be calling me to let me know when the work was done. He smiled and said no.
Member
Heating your blade to blue is going to be very risky about warping it. Spring temper can vary depending on the hardening temp they put the saw through. Back in the old days they did not have accurate means of determining oven temps,which causes variations in the quality of antique tools. Normally the temp for spring blue would be about 750º. BUT,kitchen ovens heat differently in different places inside. AND_AND_AND there can be as much as 75º difference in the TRUE temperature you have set vs. what the oven actually heats to.
The best thing to really do is cut your blade up for making scrapers and buy another old Disston saw. Even I would not want to try heating a large,thin saw in my pyrometer controlled PROPER heat treating furnace,for fear of a permanently warped,twisted,or convex surface on the treated blade.
I think Disston might have made some specially hardened saws that were for sawing reclaimed lumber with possible stray nails in them. They were not re sharpenable. Anyone recall anything on that? I'm forgetting things at my age.
Do the Amish have phones? I thought they did not want wires connecting them to the outside World. Or even radio waves.
Last edited by george wilson; 10-16-2015 at 2:06 PM.
Contributor
I don't sharpen saws. Fortunate to always have had good sharpener around. Common for just a few teeth to break and the rest be ok, but probably hard on files. In real bad cases some got re toothed but no attempts at heat retreating.
[OP]
Member
OK, I'll abandon the thought of messing with saw blade temper.
Amish (and Old Order Mennonite) and phones: I think this largely depends on the church they belong to. Some will have a phone, housed in a shed away from the house and barn, often down near the road. If they are really progressive, it will have an answering machine with it. This guy apparently is not a member of such a congregation.
Adoption of technology varies very widely. Around here you can find barns electrified, but not the house; electricity in the barn would be used to refrigerate milk and light the milking stalls. It is OK here since it is not a luxury. You can also find horse drawn wagons that have gas or diesel motor driven bailing machines mounted on them. No tractors, horses. Others may have tractors, but no rubber wheels; steel wheels. Very hard on roads they are.
Last edited by William Flather; 10-16-2015 at 4:00 PM.
Member
William,
Disston made a very hard,famous and valuable cabinet makers saw called the ACME 120. It had a VERY hard blade and was filed to run with no set, the teeth can snap if you try to set them. If you have one suggest you send it to Matt Cianci, an expert on these. When I hand filed mine the blade was almost as hard as the file!
[OP]
Member
Doug, I don't think I have an Acme 120, but i'll check.
Member
The chart I looked at said 560 degrees F for High carbon for spring steel dark blue. Try it on a junker first. Let it cool off in the even so it cools slow.
Member
Disston never advertised the Acme 120 as being harder than their other saws. The model 40 was a handsaw for metals, but the teeth were very fine, as one would expect.
I have come across both No. 7 and D-8s that had some hard teeth that broke when I tried to set them.
As far as heating and warping, there will be no warping if the whole plate is heated evenly and cooled evenly. Evenly is more important than slow cooling, though it's hard to do the first without doing the second.
I tried to retemper a D-8 plate but couldn't get it hot enough in the kitchen oven. No warping though.
Jim
Member
Charts vary widely about tempering temperatures. It also depends upon the alloy of the steel you are tempering. One size does not fit all.
As I mentioned,kitchen ovens do not heat evenly. (That is the problem,at least partially) Not even for normal baking of foods. On the "British Baking Show",which I watch with my wife,the contestants are always moving biscuits,muffins and other small baked goods around,re arranging them on the baking sheet. Some are getting browner than others while some aren't baking fast enough. This happens all the time when they bake small items.
I tried to fire blue a pistol barrel many years ago. Could not get the whole barrel to evenly blue. In my Paragon 22" deep knife maker's electric furnace with pyrometer control,I have no problem getting items of different mass within themselves(I.E.,a flintlock pistol barrel that has a much thicker breech and a thinner muzzle) blue all over. I still would not want to blue a thin saw blade in it because it will get stresses released and will warp.
Last edited by george wilson; 10-17-2015 at 9:30 AM.
Member
?????Originally Posted by Jim Davis
From Disstonian institute "The Disston 120 or "Acme" saw was a special model made from 1876-1924. It features an ultra-tapered and hardened blade, filing with tall, narrow gullets, and no tooth set."
From Disston 1924 catalog
"The Disston No. 120 Acme Saw is not an ordinary type of hand saw and should not be used for ordinary work. It is designed for sawing dry, seasoned lumber only, and cannot be used successfully for general work. It is a fast, smooth-cutting saw for fine cabinet work, sawing mitres, etc. It will cut a joint sufficiently smooth to glue without planing, and is very popular with those doing extremely accurate sawing. It must be kept properly sharpened and should not be set. The Disston six-inch cant safe-back File is made expressly for filing this saw. The No. 120 Saw is very high in temper. The blade is specially ground for clearance and the teeth require no set."
Member
I agree with you on all points George. If someone wanted to try this I thought the lower temperature, if it worked, would be a better bet as the home oven can't get up to 700 degrees and you can always do a higher heat later. It is far and away easier to find another saw, but there are experimenters in the mix. A convection oven would help as well.
Member
"High in temper" does not mean "hard." In fact, it means nothing specific. Temper is the amount a piece of steel is softened after hardening. "High temper" was just an advertising term to present the idea of very high quality.
Posting Permissions
Reply With Quote