4x6 Bandsaw modifications

I recently completed some modifications to my Harbor Freight 4x6 bandsaw. 

I added a collection chute for saw swarf, vise jaw extensions so I can saw shorter pieces of stock, two jack "screws" to help keep the movable jaw from tilting backwards when clamping, and a jack rod to stabilize the movable jaw in the other axis.

The above photo shows the chute on the right.  I used some scrap sheet metal left over from our house project and a small metal bender (also purchased at Harbor Freight) to form the sides.  I drilled a couple of holes in the casting and chute to bolt the chute to the saw.  This arrangement doesn't capture all the swarf but it's far better than my previous setup, which was a paper bag taped to the base with duct tape.  It didn't take long for the tape to get crudded up with swarf and cutting oil, so I had to re-attach the bag every time I wanted to use the bandsaw.

You also can see two brass #10-32 "jack screws" on either side of the 14mm bolt used to attach the movable jaw to the screw nut.  They are used to stabilize the jaw so it doesn't rotate away from the stock as much when clamping it.  I faced off the ends of the screws to maximize the contact area between the screw and bandsaw table; and the brass won't scratch or mar the cast iron (I hope).  Finger tight is good enough for this.

The jack rod, on the left side of the jaws, is used to keep the movable jaw from rotating away from stock on the other axis.  In use, after the stock is lightly clamped the rod is run up to the fixed jaw and clamped in place.  Then the jaw is tightened down to secure the work.

 
This is a different view showing the jack rod and how I hold it in place.  I drilled a 1/2" hole in the plate, then used the band saw to cut a slot from the bottom of plate up to the hole.  There are two steel blocks mounted to the plate, on either side of the slot.  A 1/4" bolt feeds through the block that is visible in the photo and threads into the other block.  Tightening the bolt closes the slot and pinches the rod in place.  Actually, I had to widen the slot using a carbide end mill -- otherwise there wasn't quite enough closure to securely hold the jack rod.  If need be I can remove the rod for large items I'm cutting -- nothing else protrudes past the surface of the 1/4" thick plate.  There is a lot of mechanical advantage at work here -- the screw and the lever action -- so once the bolt is tightened that jack rod is going nowhere.

I'm using a piece of scrap aluminum rod, no need to use steel in this application.

Harbor Freight wire welder modification

Something I haven't done much with yet is welding/brazing to fabricate items.  I've done a lot of soldering, which is pretty similar to brazing so that doesn't present much of a challenge (so he sez).  Welding is a different story, and looks to be a very handy skill to have.  I started looking into inexpensive learning-level welders and found some info about modifying cheap Harbor Freight  welders, from pretty crappy AC to sort-of-OK DC current welders.

The basic approach is to take your HF alternating-current welder and turn it into a DC welder, using a high current diode bridge and large-value electrolytic capacitor.  This requires some serious mod work, cutting wires and installing the rectifier/capacitor inside the welder.  I bought the rectifier and capacitor on ebay (BTW, this type of modification is described on a number of web sites so I don't think it is necessary to go into much detail here). 

I also got some 10 gauge multi stranded wire and spade type connectors to match, to make sure the connectors and wire would not limit the current available for welding.  Wire this size is pretty stiff so it is necessary to think about the physical arrangement of the wires/diode bridge/capacitor so you are not exposing the device terminals to excess stress.

I finally completed the mods but was not totally confident that everything was wired up correctly.  To verify the wiring I performed an incremental power-up test.  I began by using an external 40V power supply.  I used it to bias up the capacitor and (hopefully) back-bias the diode bridge (it should look like an open circuit).  Everything looked OK so I plugged the welder power cord in, took a deep breath and flicked the power switch.  Nothing, nada.  Well, not all bad -- no smoke.  But not great, either.  So I cussed and opened the welder back up, and discovered I had not reconnected a connector on the controller board.  Well, that's better than an egregious wiring error I guess. 

After plugging the connector back in, the welder powered up OK.  Some trial runs produced results that clearly showed I need some practice making a good bead -- not too surprising there, but I got some good metal puddles that show promise. 

I started out with the slowest wire feed rate and just got "bangs" as the capacitor charged up and blew out the welding wire.  Now I'm up to about the halfway point on the feed-rate dial (whatever that means in physical terms) and get a more or less continuous arc.  I ran some beads across the surface of some iron plate I had for the testing.  The next thing to try:  gluing some metal pieces together to see how well this metal glue gun works.

Fun stuff.

By the way, while doing the welding tests I wore protective gear, including a welding helmet with eye protection.  The ultraviolet light from arc welding is hazardous!  Heed all warnings that come with your welder.