8 June 2014 at 1:40 am #57987Philo_Beddoe12Participant
A few months ago I bought a couple of old, rusty Disston panel saws on Ebay for cheap (I think I paid $14 for the pair, not including shipping). I had planned to use these as my practice saws for my first attempts at saw sharpening. I asked the seller if the blades were straight before bidding, and I was assured they were. Turns out they were not, not even close. Still, for the price, I couldn’t complain.
I compiled blog and youtube tips from several places, and figured I’d give straightening a shot. I was amazed at how well they both turned out with just a little trial and error. I want to strongly, STRONGLY encourage people to try straightening for themselves! Unfortunately, my crappy camera couldn’t get good pictures of the kinks and bows in the blade, but I will post some photos of the restorations.
I didn’t have an anvil, so I went way simpler: A piece of straight, flat scrap MDF on my concrete floor. I tried using it on my workbench, but I think there was too much flex in the bench for hammering out kinks, even directly over the leg. I also used a small sledge hammer, I’m guessing 3-4 lbs, that had a broad, round face.
I took the handles off and released the tension in the blade by bending both ends together in both directions. (A note about tension: I don’t know if my tension steps are necessary or not. The Bob Smalser blog talks about it, but it’s not really something I can test or see. It may be mumbo-jumbo, but I did it and I’m happy with the way it all turned out). For the bow, I just held the saw toe down to my bench with one hand and gently bent the rest of the blade in the opposite direction of the bow, with the arc right over the bowed spot. I think holding the bend in place for a few seconds worked better than bending and immediately releasing. I checked the blade frequently and I could see I was making progress.
Now the kinks… I thought this was going to be far trickier that it actually ended up being. Please keep in mind this was my amateur, fumbling way of doing it and I’m sure there are a dozen ways to do it. The important point is it worked so don’t be afraid to jump in and try it! As I said above, I used an MDF panel on my concrete floor as my anvil. I did have to move the panel around a bit, just because my floor was not perfectly flat. As you tap the blade with the hammer, you can hear a difference whenever you’re on a perfectly flat spot on the floor (good) or when there’s a bit of a gap between the MDF and the floor (bad). You don’t want there to be any flex that can absorb the force, you want it all going into the saw. All I did was sight along the blade and the back to find my kinked spots, mark them with a colored pencil, laid it concave side down and then tap those spots.
What do I mean by tap? I used no downward swing at all, I just raised the hammer up about 6-8 inches and let the hammer fall, being careful to hit it square. I tapped 1-3 times right in the middle of my mark, then 1-2 times in all directions around it, about a 1/4″ or 1/2′ away from my mark. I checked it frequently and sighted down it and repeated until I had it straight. Don’t forget about checking and working the back spine, too! I also found some spots just by pressing down on the blade while it was laying flat and finding spots where there was a bit of give and spring. I think this whole process took less than half an hour. How straight is it now? Pretty flippin’ straight. If you know they’re there and you have really good light, you can still see a bit of variation, but my wife couldn’t see it (at least she said she can’t. She’s pretty supportive.) Now, I planned to saw-set my teeth anyway, so I didn’t worry about hitting them. Keep the set in mind if you don’t intend to, and avoid hitting the teeth.
Once I was happy with how straight it became, I took a smaller hammer, a ball peen, and re-tensioned again. I laid the saw flat on MDF on the floor, started at the toe, aimed for 1/2″ above the teeth, lifted the hammer only an inch or two this time, and let it drop. I then moved towards the heel about 1/2″, and did it again. Went all the way to the heel, flipped the blade over and did the same thing on the other side. I put the blade back on, sharpened and set it, and it cuts a perfect straight line!
I really hope this gives someone the confidence to try it for themselves. I think it’s another one of those skills that gurus and experts have overcomplicated. I truly believe if I can do this, then anyone can. Save an old saw from the junk pile and give it a place of honor on your workbench, where it belongs. Just be patient and keep trying!
You must be logged in to access attached files.8 June 2014 at 8:33 am #57994Michael PetreParticipant
I have successfully straightened small saws in the past by using a club hammer as the anvil.
On the subject of plate restoration, if you can remove the handle, a week long bath in a 9-to-1 water/molasses mix followed by a light scrubbing with a brass brush does miracles for the rust. I have restored old rusty saw plates, files and rasps with this method. You absolutely need to give them a thin oil coat after that, otherwise you will get some flash rust.
Saving old tools from the junk pile is a lot of fun 🙂8 June 2014 at 9:35 am #57996George BridgemanParticipant
Great write-up! Good to hear from someone else who has tried it.
Regarding detensioning. Ron Herman also does this first in his DVD on raw restoration. If the saw is already has no tension you won’t notice a difference. The tone you get when hitting the plate with your knuckle says a lot about how much tension is in the steel. A well tensioned saw sings!
"To know and not do is to not know"10 June 2014 at 8:58 pm #58209bowParticipant
Many thanks, i’m trying to do the same with a very hold 18″ hand saw..10 June 2014 at 10:46 pm #58218Eddy FlynnParticipant
i know what tomorrows job will be thanks for all the hints and tips
Eddy .. Liverpool, Merseyside, UK
,12 June 2014 at 12:09 pm #58440timmerParticipant
Thanks very much for this. Had to straighten a minor bow out of a disston I’m renovating as a present for father’s day, and this worked perfectly!13 June 2014 at 10:33 pm #58507STEVE MASSIEParticipant
I haven’t tried this yet but do have a couple candidates to practice on. I am gathering all the necessary tools for saw maintenance, files, vise etc. I can see this becoming addicting.
Enjoyed your write up also, thanks for sharing.
Steve Massie, I live in the great State of Florida, US15 June 2014 at 12:22 am #58521Philo_Beddoe12Participant
Glad I could help! We’re all in this together!20 June 2014 at 10:41 pm #58681Salko SaficParticipant
That is some wonderful information there.
The Lost Scrolls of HANDWORK
(Hand tool only woodworking magazine)
- You must be logged in to reply to this topic.