[How do I?] ...she's Gorgeous Running! Bandsaw Welder. 440vac. Convert To 220vac

countryguy

countryguy

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Hi gang, The Grob 4v-18 is home. The unit was 440Vac with the motor now setup for 220 3 phase. This leaves the bandsaw blade (butt) welder to solve. I have no blades, a bunch of blade stock. And no way to make a blade just yet.

The butt welder pulls L2 and L3 from the main power source to run the large butt welder Xformer.
If I elect to try it w/ my 220 L1 and L2 then I get a a muh lower current draw but would it work?
If I halve the voltage I will halve the current flow and it would mean that the heat up time would need to run longer? I popped in a note to Grob to see if they have a config for the 1983 welder transformer version and any setup connection 220. The print from 2008 does reflect a single Xformer w/ both hookup options.
buttWelder-photo.JPG
 
Grob (great people there!!!) had an engineer get back to me. only thing to do is boost up my 220 to 440 and hold 10-12 amps. I see on other posts (was it recently here? I know I was just reading about this) to boost by running a 2:1 transformer in reverse? Put the secondary coil on the 220 input and boost feed the butt welder from the Primary side. I would say 5 to-7KVa w/ a 440/220 Xformer wired in reverse if I follow the threads I see out there in Net land. Hmmmmmm thinking aloud. Might be cheaper to just buy soemthing that comes w/ a large transformer and pull it out? HF? TSC? etc...
 
Really? That would be awesome too. Hmmm... I have the regular ol' Tin/Lead stuff for pipe and some propane and am very good at soldering. I also have a 220Vac spot Welder. I was going to try to hit between the 2 blade ends and see what damage I could do that way also. Just wired it up to the RPC panel. This bandsaw is going live tonight! ;-
 
I think I would go with the 3KVA 240/480. There is really no primary or secondary, they are made to be wired either way, step up or step down.
 
Make a guide to hold the blade in alinment with a gap to get your heat in, have the blade ends overlap and with a thin cut off wheel in your dremel cut the blade on an angle . If you do it right you will have just enough room to silver solder and the joint will work just as good as a welded joint.
 
3Kva transformer primary connected as autotransformer will give you what you need. Only1/2 of the current will flow through the transformer. Cap the secondary wires.
 
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It sure would be nice to have the blade welder built into the machine fully functional, but a band-saw blade silver soldering kit would be much less expensive than those transformers.
I have never needed to fix a blade for my metal-cutting band- saw; because 1) I do straight cuts almost exclusively and therefore use a wide blade, and 2) I dull them before I break them!

For the wood-cutting band-saw, I have broken some making small radius turn cuts in hardwood. This kit works well for me:
http://www.leevalley.com/en/wood/page.aspx?p=41049&cat=1,41036,41048
However, after using it and seeing how it works I'd probably just make my own now.....

The Aug/Sept issue of Machinist Workshop had an article on band-saw blade soldering.
What I liked about that jig is that although it was not adjustable for blade width, it was sturdy.
Picture a flat c-shape of aluminum with a milled out shoulder to align the back edge of the blade ends; they also milled another recess for tooth clearance.
The jig had two de-sta-co-type toggle clamps to hold the blade ends.
That article also showed overlapping the ends and cutting the scarf angle in both ends at the same time with a dremel mounted cut-off wheel. (as David mentions above)

I am usually repairing blades rather than making them from roll stock, therefore I do not want to remove much length; I just use my bench grinder to square and then scarf the ends.

-the large diameter band-saw wheels stress the solder joints much less than small dia. wheels
-I usually run my fingers over the joint after repairing(and free-air cooling!!!) to feel for any thick spots; a little touch on the grinder, sander, or dremel quickly cleans it up
-if you can hear the joint going thru your blades guides, you should touch it up
-the flux in that kit dries out quickly even in the closed container, but can be re-constituted with a little water
-if you build your own jig, you could get the solder and flux refill from the link above.

-brino
 
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