DoAll DBW-1 Bandsaw-Blade Welder
Revision as of 07:14, 19 October 2012 by Djscholl (Updates for work progress)
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.
- 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.
- 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.
- 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.
- 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.
- 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.
- Continue welding trials with bi-metal blade