Welding Bandsaw Blades

[tmeinc]

Hi Folks

I have a Powermatic/Houdaille bandsaw blade welder that is probably 20 years old but has had very little use. I am using it to weld 1/2" x .025" blades for my 4" x 6" bandsaw. The blades are carbon and bimetal, and the tpi varies from 10-18. My problem is very inconsistent welding results. I cut the blades with aviation snips, square them with the built in grinder and wipe the ends with alcohol to remove any oil or contaminants. I always grind the ends figuring this gives a flatter contact surface. Near as I can tell, the clamps are lined up very well and the blade ends are in contact with a maximum gap of maybe .003" or less. I also set the "gap" in the unit to the value specified in the owner's manual so the current cuts out at the right point during the weld.

The detents for the clamping lever on the welder are not labelled, but I have found that the mid point works best for the blades I am welding,and that works out because the welder has a capacity of up to 1" blades.

After welding, I anneal from red heat and then put the blade on a fixture I made to file the weld down. I have better luck filing than grinding on the built in grinder. After filing, I anneal again from red heat.

As I indicated, some welds last awhile (but nowhere as long as a factory welded blade) and some fail rather quickly. I would appreciate any helpful information. Thanks in advance

 

[hdrider63]

I don't claim to be an expert but I was told to anneal only after the weld, not twice...??

 

[Edster]

I have a 1975 doall bandsaw with a welder. From what I read when you anneal the blade should just start to glow a deep red, that's as hot as you want to go. And you should anneal after the weld and after you grind.

That said most of my blades work for a while but when they do fail it is almost always at the weld. I've bought some pre welded blades for my saw latley and I have yet to break a weld.

 

[Steve in SoCal]

Take the jaws off and stone/sand them on a flat plate, the surfaces that touch the blades. Annealing may be too hot, dull red with an emphasis on dull, if you see the red as bright is normal shop light it is too hot. When you finish the weld you temper the joint with the anneal button. Temper or draw the blade to about the same color as the rest of the band in quick pulses.

Steve

 

[Holescreek]

When I was being taught on a Doall blade welder old Hans told me to release the pressure on one of the clamps during the anneal. -Mike

 

[67Cuda]

In addtion to what Steve in SoCal has said. When you are dressing the blade ends, if you can twist the blade to where you have both ends together with the two cutting edges opposite of each other. This way when you place them opposite of each other in the welder thay will match up exactly. Not sure if your blade length will allow you to do this.

Grind a tooth or two off of each end to accomodate the blade coming together when welding it.

Also, if your use snips to cut the blade, make sure you grind out any deformation of the blade end.

Other than that, just fiddle with the gap, heat and pressure setting until you get good results. Every welder is different.

To check the weld, flex it in a tight "U" inside and out.

Bi-metal blades are more difficult to weld.

Tom

 

[Armenius]

If the welds look good, ie. continuous across the blade width and a nice reinforcing bead on top and bottom, the problem lies with the annealing.

But first correct any welding problem; I found the amount of upset during the welding cycle to be particularly important...too little upset resulted in incomplete fusion... too much upset squeezed out all the plastic steel leaving a poor weld.

I use DOALL blades in 100' rolls; got them cheap somewhere, probably because they were somewhat substandard.

On the blade container it states "Anneal weld at lowest heat-only a faint red colour should be seen in shaded light".

Once I stuck to this annealing heat, weld failures became exceedingly rare.

Arminius

 

[MwTech Inc]

Go to DoAll 's site and download a book on the DB-style welders.
In there will be very specific instructions on blade welding.

I have had 0 problems with my DoAll welder and its an old DB-1, in the 40's.(completely refurbished before using)

It's techinque to get a good weld.

Cut 3-4" pieces and adjust from too cold to too hot. Find out just how the welder works.

Make sure the jaws are clean, a buildup of heavy dust can affect welding. Make sure the jaws have good electrical connections inside the unit. Any loose connections, etc will affect the weld.

Assuming your welder operates like a DoAll ,the moving jaw must move the correct amount and distance, this is critical.

 

[HuFlungDung]

I've had the most trouble with welding the small thin blade material. The electrical current seeks the shortest path always, so if the problem seems to be burn through at the back of the blade, try to grind a gap so that the initial contact point is at the front of the weld.

Have patience when annealing the weld. There is no particular need to ramp up quickly to the dull red heat, and when that temp is attained, reduce tapping on the anneal button so that the temp declines more slowly as it leaves the dull red. For the second anneal after grinding, try to jog the anneal button very carefully to build a uniform color band across the weld. The second anneal does not need to go to dull red again, IMO, just blue is good enough.

For grinding the weld, I simply clamp the blade in a vise with a bit of an arch in the blade so that the weld zone is on top of the arch. Take an ordinary 4.5" angle grinder and grind the weld flat. It's easy to see what you are doing, just sweep across the weld until you get to the base blade height. Then turn the blade inside out and grind the other side.

 

[moonlight machine]

My1954 DoAll saw has the factory original blade welder. I works great on old style carbon steel blades. It will not work at all on bi metal blades. Any one have any idea why? What is different about the newer ones?

 

[Steve in SoCal]

A number of butt welders are designed for carbon blades, some can weld Bi-metal some can't. Most of these don't weld bi-metal band too well. My welder is a 8KVA and it is rated to weld carbon bands to .035 x 1" but is limited to .035 x 1/2" bi-metal. A lot has to due with how much current your welder can muster.

Steve

 

[kpotter]

When you anneal you need to do it for a minute or two not just push the button and let it go. Spend a while annealing and the blade will last.

 

[WA Toolman]

I worked one place that had an old DoAll with a bad welder.I found silver solder worked pretty good.

 

[moonlight machine]

I made a fixture to hold the blade ends in line, I tig weld them now.....

 

[Ed ke6bnl]

I made a fixture to hold the blade ends in line, I tig weld them now.....

moore detail on your tig welding proceedure is appreciated thanks ED

 

[Mohawk72]

I too twist one blade before cutting.

I then cut through both blades at once and try to make the cut between teeth.

This way you have two teeth very close to each other to kinda protect your welded spot.

But if you don't twist the blade you have the opportunity to Cut and weld the blade at an angle, Making the welded part stronger and not so prone to breaking.

Annealing is the big trick though.

Some of my jobs require that the blade be cut, removed from part and welded while inside the next part.

So we got good at it.

Good Luck

Mohawk