Machining Steel as Part of a Tool Fabrication

I want a parallel fence for a tool (Knapp sliding saw) that's no longer in manufacture. Brian Lamb makes an absolutely elegant beautiful version (including one with a very neatly integrated DRO) but it's priced higher than I felt was justified for my purposes. Plus I wanted one that more closely resembled the manufacturer's original design. I created the design in 2-D in Adobe Illustrator generating files that I used in Sketchup to generate the 3-D mockup. Both of those designs are shown below. Using the 2-D I generated a DXF file that I sent to several Waterjet Shops. The quotes came back in the $200 to $400 range ... again, more than I wanted to spend.

So this morning I took some 1/4" high-carbon steel plate I had lying around, punched the corners of the design, struck lines and chopped off the pieces I didn't want. I then drilled and tapped and bolted together the two plates which should be essentially identical. Square everything up and of course now I'm at the hardest part (green circle illustrating on 2-D drawing) where I need to cut the notch which will hold this on the rail. My plan had been to do this with a jigsaw and metal cutting blades. I'm not in a particular hurry. I was going to finish with files. I was hoping to avoid welding on the tabs though that would likely be easier.

The "bar" (and 8020 40mm square) is readily available inexpensively on Ebay.

Is there an easier way?





Not sure if this is the right section of the forum ... I'm sure the moderator will move if not.

Bill, I would carefully layout the finish cut lines and drill the largest hole I could fit within them, in this case, ~ 5/16", and file the rest. For me, that would be cleaner & easier than fighting with a saber saw.

Water jet cutting is relatively expensive. I would look for a small machine shop, take your material and your drawing with you and see what they might charge for the cuts you need. Machining those two notches should take about an hour. You might want to get the three pieces welded together before machining the notches to get the best alignment.

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Originally Posted by Bruce Page

Bill, I would carefully layout the finish cut lines and drill the largest hole I could fit within them, in this case, ~ 5/16", and file the rest. For me, that would be cleaner & easier than fighting with a saber saw.

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That is a good solution. I think drilling and then cutting and filing is the "yankee" approach to getting this done., Thanks!

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Originally Posted by Lee Schierer

Water jet cutting is relatively expensive. I would look for a small machine shop, take your material and your drawing with you and see what they might charge for the cuts you need. Machining those two notches should take about an hour. You might want to get the three pieces welded together before machining the notches to get the best alignment.

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Lee ... that approach would be likely to produce the best results. Thanks for providing the "sober" answer. I think I'm going to try Bruce's solution (and probably regret it).

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Originally Posted by Bill Adamsen

Lee ... that approach would be likely to produce the best results. Thanks for providing the "sober" answer. I think I'm going to try Bruce's solution (and probably regret it).

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Bill, I wrote this earlier but lost it somehow... Do you possibly have a friend with a plasma cutter? The one I have will cut that size (even up to 1/2") quite cleanly, but I'm a long way from CT. I would make a little template to cut smoothly just inside the line then dress it to the line with whatever means was available. My first choice would be the mill but files, grinder, etc could work.

A vertical metal cutting bandsaw could also easily cut the parallel lines and hack out the diagonal line. (The horizontal saw I have rotates to vertical with a little bolt-on table.) Anyone who plays a lot with metal will probably have one like it, or at least a portaband. I've also used jig saws on steel but a larger recip saw (sawzall-type) with a good bimetal blade would be better for that thickness, but they are less precise than the bandsaw.

JKJ

John ... definitely looking for that friend who might have a plasma cutter. Apparently I hang in the wrong circles!

I drilled out the corners and cut using metal blades with my Dewalt battery powered jigsaw. Then finished with a hand file. Probably took about 2 hours including standing around thinking about it. It looks like it is going to work. A few more holes to drill and I'll be done. Thanks guys for the encouragement.

Looks good, Bill.

Looks as good as if done on the milling machine!

JKJ

Update ... stopped by my local ironworks today and he kindly cut me a piece of 40mm x 40mm x 19mm steel I needed to finish the fabrication. After dressing it square I had the ridiculous idea of using superglue to temporarily hold the assembly together so that I could finish drilling the holes. Amazingly it worked! I bored, countersunk and tapped all the holes and then assembled. Went together like a charm. There is a little problem with the 8020 linear bearing (carriage) which once I work that out, the unit will be functional. I used the Wixey tablesaw measuring unit which mounted readily to the 8020 extrusion (40 series) after a minor mod. The unit mounts to the saw slider as expected and should be a welcome addition.

Looks great Bill. A little prime & paint and it will look factory.

Completed the assembly, mounting the linear bearing after fitting the brake to the bearing. Yes it can use some additional design, but it works and I don't see the approach changing significantly. Calibration is simple ... slide the bar to just touching the sawblade and zero the Wixey unit. Set the distance (in this case I chose 8-1/2") and set the same distance on the saw's main fence. Cut the test strip and measure to verify and indeed it works as expected.

Some of the benefits of this system (over other parallel fences) is that the fence extrusion and Wixey unit do not need to be removed from the saw to cut large panels. Just slide off the linear bearing and the surface is below the slider tabletop. Return the linear bearing carriage to the extrusion and the calibration will have been retained. The remaining extrusion can also be easily removed, or it can easily be removed as a unit with the linear bearing and Wixey in place for storage.

This was the first time I had used the 8020 family of extrusions and parts and there was definitely a learning curve. In fact, while I likely spent just four to six hours in the shop doing the fabrication, the amount of time pouring through the catalog and trying to figure out what to do ... oh my goodness, interminable.

Total cost of the parts and shipping plus consumables (for instance sandpaper and sawblades) was $213.19. I learned a lot and had fun doing it.