DoAll DBW-1 Bandsaw-Blade Welder

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DoAll DBW-1 Bandsaw-Blade Welder

This highly specialized welder is really only useful for one thing: repairing broken bandsaw blades. It is also called a buttwelder, because the technical name for the type of weld it makes in the blade is a butt weld.

Basic Info

  • Ownership: TBD, best contacts are Dave Scholl or Steve Hermann
  • Location: The welder is installed on the south wall of the west end of the machine shop. These welders were usually installed inside the frame of a bandsaw, but this one was extracted from its bandsaw some time before it was brought to i3.
  • What it looks like:

bandsaw-blade welder photo

The welder was originally made in the 1940's, and has been painted at least five times since then. Under the many layers of paint, most of it appears to be original. The main contactor is labeled with the date "Sep 1941".

Manufacturer Information

  • Make/Model: DoAll DBW-1 Buttwelder
  • Part Number: S/N (unknown)

Documentation

  • Pdf's of the original manuals may be downloaded from this product support page on the manufacturer's website. We recommend reading both the original (DBW-1) manual and a newer manual, e.g., for the DBW-15. The newer manual covers bi-metal blades.
  • To assist with the repairs, we have created an electrical schematic drawing.

Rules

  • The welder is designed and installed for intermittent operation. If you have more than one blade to weld, please give the welder components time to cool down between welds, and only run the grinder while you are grinding.
  • Please don't adjust the heat switch (slotted screw head). This is not a user adjustment. It should always be set to the third detent, counting from the lowest heat (etching pencil) toward higher heats.

Instructions

  • The welder uses the table saw's power cord, so you will need to unplug the table saw and bring the cord around the corner. Please plug the table saw back in when you are done welding.
  • Only one user adjustment (force) is required to accomodate different blade widths.
    • 1/8 in. blade: on the "N" in "NARROW"
    • 1/4 in. blade: between "NARROW" and "SAWS"
    • 3/8 in. blade: on "SAWS" (between "NARROW" and "MEDIUM")
    • 1/2 in. blade: on "WIDTH" after "MEDIUM"
    • The optimal force settings may change if the jaws are realigned. This is because the friction in the moving jaw mechanism is extremely sensitive to the clearance of the alignment gibs.
  • The jaws are not deep enough to weld 5/8 in. or wider blades properly.
  • Vise-grip pliers are recommended for holding blades during pre-weld grinding.
  • The back corners of the jaws are worn, so simply pushing the blade back into those corners is not enough to guarantee that the blade ends are parallel. It is necessary to examine the blade ends from above to manually align the back edge of the blade before tightening the knurled screws.
  • The welder only has one blade thickness gauge: for 0.025 in. thick blades.
    • The welder can weld 0.032 in. thick blades, but you will need to use a micrometer to check the weld thickness.

Other References

  • One particular i3 member, who is a bit of a wag, has been claiming to anyone within earshot that if you have two butts on or about your person, this piece of equipment will weld them together into one butt. Don't worry, nothing could be further from the truth.

Maintenance

  • The 220V light bulb was purchased from Mouser
  • The blue insulating sheet material is 0.016 in. DMD (Dacron-Mylar-Dacron) from an electric motor shop.
  • The grinding wheel was purchased from Production Tool.
  • Two failed rubber screw-tips were replaced with machined Delrin (made by Steve H.)
  • With 243VAC on the primary, the open secondary voltages are as follows:
    • Anneal: 0.93 VAC
    • Etching: 1.65 VAC
    • Less: 3.00 VAC
    • LessLess: 3.27 VAC
    • More: 3.52 VAC
    • MoreMore: 3.80 VAC
    • These open-secondary voltages are higher than the nominal values listed in the manual, apparently because the nominal primary is 220VAC and our primary is 243VAC. This is the reason why the heat setting should not be adjusted by users.

Things that Need to be Done

  • Continue welding trials with bi-metal blade

FAQs

  1. Has anyone else ever repaired one of these old welders? Yes, someone rebuilt an entire 63-year-old DoAll Bandsaw, and rebuilt the welder as part of the project. Photos and written discussion are available on this thread in The Garage Journal. The URL is to page 5 of 26 pages, which is in the middle of the section that discusses the welder. The same author has made over a dozen videos of this project. They are available in the YouTube channel for APmachinist. Blade Welder Parts Repair is #14 in the Bandsaw Rebuild video series, and is one of several videos that discuss the welder. Note that the author's welder is model 1A, which is more recent than our model 1, and features different electrical adjustments, among other differences.
  2. Can bandsaw blades made with newer technologies (1950 or later) be repaired with this welder? Yes, if the annealing instructions from the manual for a newer model, e.g., the DBW-15, are followed.