DBW-15 blade welder -- hints?


Awl --
I got my grubby li'l hands on the above (extended loan), which is good for
up to 1" blades -- a bench-top model. I've welded 1/2" blades a long time
ago, and had great success, but have not had such great success recently
with the smaller 1/2" DoAll blade welders on 1/2" blades. Not sure if it's
me or the welder.
I've got dozens and dozens of accumulated broken and mis-sized blades, 1/2",
3/4", and 1" that I'd like to make usable, and would just like a heads up on
how to get good results.
This unit does not have a blade chopper, but I have a chopper ditty on a
DoAll-mounted (small) blade welder.
Should I use this chopper, or just an abrasive chop saw, with the two ends
overlapped?
What sized burr/flash should I look for at the end of butt welding, for each
sized blade?
How do I know when I've annealed long enough?
The annealing button has a little doo-dad to hold the annealing button down.
Seems like this anticipates a long-assed annealing time.
Is the "min" on the blade dial for 1/2"?
etc.
tia
Reply to
Existential Angst
Loading thread data ...
(Bandsaw blade welder?)
Intimate details:
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Have a look at Page 7 for the annealing scoop.
--Winston
Reply to
Winston
What are "defection axes"???
Reply to
Jim Wilkins
What are "defection axes"???
We don't use them any more. They were invented for chopping holes in the Berlin wall.
Paul K. Dickman
Reply to
Paul K. Dickman
Were they silenced so the Vopos couldn't hear them?
Reply to
Jim Wilkins
They constrain the Deflection Axis Covers to torsional movement, (attached using the Ringent Circles).
Both Thingamabobs with associated Whatzits were replaced by the Defection Axis Assembly starting with Serial number 42. Chingladaras had been tried in both positions but refused to work properly. After removal, they caused breakage and loss of random parts not associated with the Electrodes.
HTH
--Winston
Reply to
Winston
As long as you still have the offog all will be well.
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>HTH > >--Winston
Reply to
Cliff
Oh WTF?
Most I've seen don't know how to weld band saw blades. Thats why they buy factory made lenghts. & the welder on the saw is a showpiece
Ok here's the skinny:
Blade ends should be somwhat sqr. When initail welding, smaller blades require less "inward pressure" to fuse thus setting will requre some experiments so you dont get a big blob for weld. Annel is the trick so its not brittle & crack. re-set the blade in the holder in the wide open position on the welder. I use the annel button by "jogging" it, till I see it just before its starting to turn red. Again experiment with your welder. The nice Do- All welders I could weld my Dad's 3/16-1/4" wood blades & 1"-3/4" .032 blades on the same machine.
There's few more "tricks" but thats the basics what I know (not much)
Reply to
cncmillgil
The HF manual specifies exactly 90 degrees square rather than having to explain flipping one blade over and hand-grinding both together at some random angle, which works fine but is much easier to demonstrate in person than to explain in writing.
jsw
Reply to
Jim Wilkins
Well ya, it is induction welding, the *good* welders actually move the blade ends together slightly as they are welded/fused/melted - so, some what sqr?-yes cardboard:no EXACTLY 90 degs? manuals are good for the basics, after that its talent/good ol know how, then: brewt force & ignorance
Reply to
cncmillgil
Gil:
Back in the day punch press die sets were bandsawn for part or scrap fall through. You'd blue & scribe your outline, drill a few holes, cut your blade, feed it through a hole, then reweld it to cut out the section of the die set you didn't want. So welding blades was an essential die making skill. Now, big die shops probably have WaterJets or Wire EDM's to do that sort of work. And you're absolutely right, proper annealing of the blade is crucial. What I did was grind off the welding "flash" then clamp it for annealing, and like you said "Jog" the anneal button but I did it just enough to turn the shiny ground part blue. Take the blade out and flex it back and forth, if that didn't break it I was good to go.
Reply to
BottleBob
Another trick that I found helpful was to put the cut ends together but with a 180 flip so that the saw teeth were opposite in direction. That way when "squaring" up the tips prior to welding, any "non-square" of one blade end was matched in the other end. Yes I found annealing to be a must. Some times I use a die grinder to remove the excess weld. Also my welder seems to work better if I make sure to lube the spring mechanism that puts pressure on the blade ends which allows them to melt together. Not a machinist but I'm learning gobs, since I started at ground zero. Stu
Reply to
Stu Fields
What happens if you jog it to red? I seem to remember doing this for 1/2" blades, never had one fail.
Reply to
Existential Angst
EA:
Here is a little more on annealing blades.
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Annealing:
After the weld is made, it is in a very brittle state and must be reheated at a low temperature to relieve the internal stresses caused by the welding process. The methodology for annealing blades varies greatly from blade manufacturer to blade manufacturer. Some blade makers recommend annealing the band once, letting it cool, and annealing it again, while others believe annealing twice is unnecessary. Some recommend that the operator anneal the blade very hot in the beginning and slowly taper it to nothing. Still others suggest bringing the temperature up slowly, holding it for a designated period of time, and slowly bringing it back down. This author has tried to compile a typical methodology for annealing from all of the companies visited through the years. The best advice for annealing most of the band saw blades in the marketplace today is to bring the anneal heat up to the desired temperature or redness, hold it at that temperature for a certain length of time (usually around 2-5 seconds), then shut the heat off and let the blade cool naturally. The actual temperature at which most annealing takes place varies from blade to blade, but the average is from approximately 1,050 to 1,275 degrees Fahrenheit. If a welding machine is not equipped with an optical pyrometer and a temperature readout, the operator can bring the temperature up slowly until redness is just visible and then begin to taper the temperature down until it is no longer visible. The manufacturers of the band saw blades can provide recommended annealing temperatures and practices for their blades. Some of the newer blades have a high degree of silicon and may require hotter temperatures during annealing. While the annealing is taking place, the operator should observe how the anneal pattern travels across the blade. The heat given off during annealing causes the band to change color for a small distance on each side of the weld. The width of the heat-affected zone generally is just smaller than the width of the jaws during annealing, and it should be parallel to the weld area from the tooth edge to the back edge. If it is not parallel to the weld on both sides of the weld, there is a current flow problem that must be corrected. Uneven clamping could be causing this problem, and immediate action should be taken to correct it. ===============================================================
But, to indirectly answer your question, a "little" red is probably is not "too" bad, but when I've accidentally put too much heat into the blade I lightly regrind the weld area to clean-up the area so as to easily see the color change and then re-anneal to blue. YMMV.
Reply to
BottleBob
BB:
I'm sending all my blades to you for welding Could you also reset the teeth & sharpen? LOL! I've not seen anybody weld blades for years now. Hell the welder on our POS vert. saw is disconnected!? not up to OSHA standards they tell me? We use the a 1" $carbide$ tipped blades for TI on an Amada horizontal. Sweeeet machine! Never seen one like that in mold shops. Has hyd feed/clamping/bar feed. Cuts straight -less than 1/64 out. Till Gil lets the blade rest close to the stock(on blade sensor limit switch) for setup, get distracted & come back about an hour later (did not know about hyd creep down) Turn it on & there goes the teeth! ~! @@##@!~~~ Lesson learned: always raise the blade up & then turn on, letting it feed down by itself. It rapids down till the sensor touches the stock (about an 1/8 away) then feeds.
We did alot of "window pocket" mold bases. Typically called "A" bases - thru pkt. Very weak design? The only advantage is you finish the pkts together for perfect alignment As you said, (4) 1" holes were drilled in the corners,blade was welded in after threading thru 1 hole. You learned how to weld blades- no choice- not many TWEDM's,waterjets ect back in 80's. Sawing is the fastest way to remove stock. Alot of shops design their molds with use of Wire EDM in mind since they are common in most shops today. Un attended night cutting is the ticket. Hell the Hurco is cutting TI all night long -lights out, a bit slower than days but safe. Oh BTW cutting TI at +400SFM dont work like MMS says. maybe for light finishing cuts? Not roughing thats for sure.
Reply to
cncmillgil
What? Super Glue wouldn't work? LOL
Here are some other manual bandsaw tid-bits.
I was taught years ago that you should always have at least 6-12 teeth engaged in the work. BUT, I've found that it seems that the fewer teeth in the cut you have the more efficiently they remove metal since there will be more chipload per tooth at the same pushing pressure. I mean if that weren't the case, then why make course tooth blades, eh? And yes, I've heard of gullet clearance. The lower limit seems to be like 3 teeth in the cut. Now when a tooth breaks off and embeds itself in your material you've got to pull your material away from the blade IMMEDIATELY or you'll dull the rest of the teeth when they skid over that hardened tooth. Flip your part over and get a piece of hacksaw blade (the shorter - the better), and pound that broken off tooth out from behind. You may have to sharpen a little digging hook on the business end of the hacksaw blade. Obviously, any blade with missing teeth in one section should have that section of the blade removed and then rewelded. But if there is a LARGE section missing where removing it would make the blade too short and you don't have any other piece of blade you can weld in, and it's like Saturday afternoon and no place is open to get another blade and your part has to ship Monday morning, you can do a Mickey Mouse count. Lightly push your part into the blade and when it goes "Ka-chunk", count the seconds until it goes "Ka-chunk" again. If it's like 6 seconds, then push hard and count to five, then let up, when the bad part of the blade goes by, start counting and pushing again. See what I mean by Mickey Mouse? LOL Before you throw that beat to death fine tooth blade away, think about saving it for "friction cutting". Smooth all the teeth down (twist the blade inside out so the teeth are facing the wrong way and and push like a 1" HSS lathe tool bit into the blade - better put it in a vise or it could rip that puppy right out of your hand). When the teeth are just nubs, flip the blade back over and then you can use it to cut really thin material by running the SFPM way up there. It will make a hellacious amount of noise, & sometimes sparks, plus leaves a burr, but it'll cut (after a fashion ). If you're cutting some thin tough stuff (like A2, or 316 stainless) and you used your last fine tooth blade to make a friction blade (LOL), and all you have is a coarse tooth blade, just clamp a piece of junk stock to your part (making it thicker) so the teeth don't snag. And of course virtually everyone knows the trick of pushing a candle into the side of the blade when you're cutting thick aluminum pieces. The wax helps to keep the blade from loading up. All you Mouseketeers sing it with me now - M-I-C-K-E-Y..... :)
Reply to
BottleBob
Minor update on blade annealing. The site I posted today in amc has a temperature/color chart. Let me copy the relevant part:
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Awww Crap, the columns wouldn't stay lined up, so you'll have to click on the site address to see the carts.
And here is some background from Wik on tempering temperatures of steel.
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Tempering in steel
Typically steel is heat treated in a multi-step process. First it is heated to create a solid solution of iron and carbon in a process called austenizing. Austenizing is followed by quenching to produce a martensitic microstructure. The steel is then tempered by heating between the ranges of (300°F-500°F) and (700°F-1200°F). Tempering in the range of (500°F-700°F) is sometimes avoided to reduce temper brittling. The steel is held at that temperature until the carbon trapped in the martensite diffuses to produce a chemical composition with the potential to create either bainite or pearlite (a crystal structure formed from a mixture of ferrite and cementite). It should be noted that when producing a truly bainitic or pearlitic steel the steel must be once again taken up to the austenite region (austenizing) and cooled slowly to a controlled temperature before being fully quenched to a low temperature. In bainitic steels, upper bainite or lower bainite may form depending on the length and temperature of the tempering process. It is thermodynamically impossible that the martensite will be totally converted during tempering, so a mixture of martensite, bainite, ferrite and cementite is often formed. ===============================================================
Reply to
BottleBob

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