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alanganes
11-14-2009, 10:04 PM
Any experts here on using a blade welder?

I have one that was originally on a Grob bandsaw. I managed to save the welder from the scrap guy when the saw was scrapped. It needed some repair, so I fixed it all up and it has all the look of working properly. Except that I can't seem to get a proper weld out of it.

I know this particular unit worked at one time. When I try it now, the blade heats up seemingly as it should, but just as the ends start to melt together, they seem to slide past one another rather than mash into each-other making an incomplete weld.

I have made sure that the blade clamps are on the same plane and move on the same line, as much as I can tell.

I could live without this, I have always either bought my blades made up, or silver soldered them with good results. And I do not go through that many bandsaw blades in a year, really. But I got it for free, and it is so darn cool that I would like to use the thing. Plus I have occasionally gotten some deals (nearly free) on rolls of blade stock.

So I'm not sure if I am missing some technique in it's use, or if I am overlooking some flaw in this unit. Is there any secret to using one of these? Are they really that tricky to operate? Any hints?
Thanks!
-Al

Oldbrock
11-14-2009, 10:20 PM
Are you sure you have the jaws in the welding position. The close setting is for welding and the far apart spacing is the annealing position. Also are the ends of the blade ground perfectly square? If not, they will skid. Hard to guess what's wrong without seeing the operation. Peter

alanganes
11-15-2009, 08:28 AM
Jaws are in the correct position, on this one you dial it up according to the width of the blade (1/2" in my case). I "Think" my blade ends are square, but maybe I'll need to be a bit more picky about checking that and give it a few more tries.

Appreciate the reply.
Thanks,
AL

JoeFin
11-15-2009, 08:35 AM
and you should over-lap approx 1/4"

wierdscience
11-15-2009, 10:02 AM
Had a Grob welder,not the easiest to use as blade welders go,but they do work.

First the ends of the blades must be ground square.

Second make sure there is no oil or dust on the blade stock.

Third clamp the blade ends in the welder jaws with a gap inbetween,usually about 1/16-3/32" wide.If the ends touch the blade ends will simply short and glow like you are getting now.

Fourth you should get a flash of sparks during welding,not a short as mentioned above.Dial back on your blade width setting until you get sparks.

Offsetting such as you are getting now indicates one of two possiblities,either too much pressure being applied during welding(see above about blade width setting) or mis-aligned jaws.

Each new roll of blade material will weld different.I usually start by cutting some 4" long test pieces and weld them until I get the settings down.This keeps from having too many"almost long enough blades" laying around:D

You can also have more than one weld per blade if you screw up and few.

Scishopguy
11-16-2009, 01:34 PM
Alan...Did you get the cutting fixture and filing fixture with the welder? I used one of those saws for years and it worked flawlessly. There was a lever operated cutting fixture above the welder that had a straight edge to keep the blade true while you cut it. Part of that fixture was a slightly rounded clamping jig that allowed you to flex the welded part of the blade over a hard surface so you could file off the excess weld before anealing it.

alanganes
11-16-2009, 03:29 PM
Alan...Did you get the cutting fixture and filing fixture with the welder? I used one of those saws for years and it worked flawlessly. There was a lever operated cutting fixture above the welder that had a straight edge to keep the blade true while you cut it. Part of that fixture was a slightly rounded clamping jig that allowed you to flex the welded part of the blade over a hard surface so you could file off the excess weld before anealing it.


Thanks to all for the replies. I only had a short while to mess with this since getting most of this advice, so I have not progressed too far. I did get some improvement by tweaking the spacing between the blade ends before cranking the knob around to the blade size position for welding. So more experimenting seems to be in order.

I did not get the cutting fixture, it was (long ago) missing from the saw this was salvaged from. I have been cutting the blade stock with a little Beverly shear and grinding them "square" using the flip-one-end-over trick so that they match up nicely.

There was a filing fixture, though it seemed to be missing when I got this thing. But it may yet turn up. Still working on that.

Thanks again!
-Al

PS- And while I do not have a collection of "almost long enough blades" around, I DO seem to have one that keeps getting shorter and shorter and shorter...

lynnl
11-17-2009, 12:04 AM
and you should over-lap approx 1/4"

Really?
The one (& only) blade welder I ever saw used, at a tech school shop, did butt welds. I thought they all did.

alanganes
11-17-2009, 04:10 PM
Really?
The one (& only) blade welder I ever saw used, at a tech school shop, did butt welds. I thought they all did.

I always knew them to butt weld, too.

As it happens, I emailed GROB, Inc. to ask if they had instructions and a schematic for my welder. I knew it was pretty old and did not think it too likely but figured that I had nothing to lose. These folks are unbelievable. They replied next day, and attached a PDF of the instructions* and a PDF of the schematic. The schematic is a scan of an obviously old-school drawing done by a "real" draftsman dated 10-11-1944(!). That sort of customer service is getting incredibly rare. And I'm not REALLY even a customer.

The instructions specify that the blade ends butt together.


*Instructions are for a newer (1950's) generation welder, but that is because I told them the incorrect year for the saw. My fault. No matter, the basics are the same.