PDA

View Full Version : Blade welder plans needed!



Mcostello
08-17-2007, 11:16 PM
Any one want to cobble up an article for the HSM magazines so that we could make a copy? Prefer steel welded butt joints.

Carld
08-18-2007, 12:46 AM
??????? blades, what kind of blades?

Ian B
08-18-2007, 01:01 AM
bandsaw blades, I'd guess

madman
08-18-2007, 09:05 AM
I'd guess bandsaw blades,

Mike W
08-18-2007, 09:33 AM
Use silver solder. You don't need to build anything and it always works.

Lew Hartswick
08-18-2007, 10:04 AM
Use silver solder. You don't need to build anything and it always works.

Well I've never tried to make a scarf joint in 0.025" thick material
but I would guess it's a bugger. While the butt welder I use is almost
simplicity personified. :-)
As to trying to make one, I think the clamp mechanism that moves
together as the weld takes place would present a real challange.
The electrics would be a snap.
I'd surely be intrested in seeing anyones approach to the task.
...lew...

Mike W
08-18-2007, 10:27 AM
Nothing to it I grind the ends of the blade at about 22 degrees. Clamp it down and heat it up with a small tip and touch the SS to the joint. Takes just a few seconds.

http://img.photobucket.com/albums/v110/tek798/Misc/Bandsawbladejig.jpg

gary hart
08-18-2007, 11:43 AM
In the English magazine "Model Engineers' Workshop" issue #41, Mar/Apr 1997, there is an article:
"Bandsaw Blade Butt Welder"
"Repair or make new blades, make a machine with a multitude of uses. Part 1"
MEW #42 has rest of article. "Spot Welder"
"A built up attachment to fit the bandsaw blade welding machine described last time"

Herm Williams
08-18-2007, 11:55 AM
Has anyone tried the SS metdod on bimetal blades or doese it make a difference?
tia
re

Bruce Griffing
08-18-2007, 01:20 PM
I don't have plans, but this guy sells an electric butt welder that uses a car battery. In the past, I have read that you can weld two 1/2" blades per charge. Here is the link.

http://www.advancecarmover.com/details.php?sku=02500&line=Band_Saw_Blade_Welders

It does not look very complex - you could probably make one like it.

Forrest Addy
08-18-2007, 01:58 PM
The only hitch I can see to a home brew saw band welder is a transformer with enough low voltage secondary Amps to flash/upset weld 0.025 or 0.032 stock by however wide. That takes a big controlled jolt of heavy current.

Just to ball park it I would think the band saw welders I've seen the guts of were maybe built around a 1 KVA transformer. The secondary was a copper strap as wide as the eye through the laminations and had only a few turns. Open curcuit voltage was but a couple of volts at maybe a thousand Amps. The current path will have to reflect this.

Heat control can be via a Variac or solid state control. The band welders I've seen had primary taps.

Anyone cooking up a design would be well advised to look at a factory made one and reverse engineer it. No point in re-inventing the wheel.

I'd first find a 1 KVA machine control transformer and de-wind the top winding saving the other winding as the primary. Wind the high current secondary through the eyes making the copper section reflect the current it passes. You need one lead with some movement possible for the moveable jaw of the welder. Use heavy copper shunt braid or multiple 4/0 welding cable for this secondary lead and keep both runs very short.

If you saw band sparks slightly and turn red you need more heat. If it flashes into sparks with a loud Sput!! and leaves a melted ruin you need less heat. Practice on shipping banding. It's far cheaper than saw band stock.

Mcostello
08-18-2007, 10:52 PM
If I only understood electricity that good we would not have this topic. can silver solder, can't seem to anneal right. Made skived joint with fixture made on surface grinder, ends require too much dressing to pass through guides as they curl slightly when soldering, hence this thread being posted.Have used DoAll welder in another life and liked it very much.

Mike W
08-18-2007, 10:59 PM
When I SS mine I sometimes just use a file to take off the slight excess left. The main thing is the jig to hold the ends in alignment before you connect them. I never have annealed, just solder them and use as is. Annealing would probably be good though.

Your Old Dog
08-19-2007, 07:35 AM
Has anyone tried the SS metdod on bimetal blades or doese it make a difference?
tia
re

I've had no luck getting them to hold. I have 3 new Sterritt variable pitch blades that I can't get to stay together using Silver brazing wire, a blade holding jig and scarfed joints. The breaks all look like crystallized metal.

Lew Hartswick
08-19-2007, 11:28 AM
k.

Yep. Everything Forest said. A good source of transformer is a 1KW
microwave . No problem re winding the secondary. The big problem
comes in the timeing the pulse and the adjusting travel for various
width blades.
Still can't quite picture that scarf joint on 0.025 x 1/2" material.
:-)
...lew...

Mike W
08-19-2007, 12:00 PM
I read maybe in MSC that two welders were shown. One mentioned it was for bi-metal blades.

Tinkerer
08-19-2007, 12:11 PM
Yep.
Still can't quite picture that scarf joint on 0.025 x 1/2" material.
:-)
...lew...
Twist blade.. butt joints and grind taper untwist and align. Flatten a little piece of silver solider and place between heat till flow and clamp with smooth jawed pliers. Smooth out sides with a few quick flapper wheel passes. Worked for me.

dirty old man
08-21-2007, 09:15 PM
Been saving worn out blades to practice on for whenever I get a chance to build a fixture to hold the blades.
Read somewhere about using a tig welder and 308 rod, no annealing needed.
I have the tig and the rod, just need to build a simple jig. Maybe one day it will get neat the top of my priority list. At the present, it's too easy to pick up the phone and order blades.
Dave

Mcostello
08-21-2007, 10:18 PM
Theres my answer! A good reason to buy a Tig machine. Knew you guys would come through. Now to find money and space, sure would like to have one though.