Is anyone else interested in rotary broaching? The holders are a bit expensive. However, I think one could be fabricated for not much cost at all.
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Absolutely.
I was advised that they are expensive and rarely needed. I agree on the former, but would argue that if we have it, the latter would be untrue.
I have been considering trying to build one, though with a few improvements on the few how-tos out there. Like this one…
http://www.docsmachine.com/projects/rotarybroach/rb01.html
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I would be interested in seeing one actually work, but can’t think of many places I would ever have used one. But if it were available, I would undoubtedly discover such places.
Given the cost of commercial rotary broaches I would say it wasn’t a cost effective purchase; however, I agree one could be made for a low cash outlay. But I suspect it would require a fair bit of ‘free’ labor to produce. I also wonder how well such a tool would hold up to the abuse tools receive at the space.
I believe a holder would be somewhat difficult to screw up (although where there’s a will there’s a way). Also I doubt it would be terribly difficult to make. Although it would require that sine bar that’s been sitting in the acquisition queue.
We actually have acquired the sine bar.
And in my opinion, anything that requires a sine bar for setup moves it well into the ‘difficult to make’ side of the spectrum.
And the above illustrated boring bar is why I think such a tool will get screwed up at the space. You have to do a number of really bad things to do that much damage to a boring bar, particularly one that was way to small to have been used in the lathe. Meaning they did that with the Criterion in the Bridgeport…
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Nothing prevents “us” from “free laboring” it into existence, and only bringing it into the space for use by trustworthy souls, as long as “we” also provide the materials…
I hate to be that way, but we don’t let “just anyone” loose on the HAAS, or the CNC Router, or the lift…
It is my intention to make myself one of these for personal use some day. If “we” wanted to, I would like to participate, even if that means I have to ask to use it, should I want to, at some point in the future, just because then I’ll know more about how to make my own when the opportunity presents. Kinda like our steam engine. Got no use for it, other than to learn. I see no reason we couldn’t learn on a rotary broach build as well, although, as stated, if the 'Space buys it, it belongs to them and will, likely be abused…
course, this way is pretty idiot proof, and likely the only thing they’d do is hurt themselves if they abuse it…
I didn’t intend my comments about the quantity of ‘free’ labor to discourage. Just saying that when avoiding the spending of cash by doing it yourself, it is real easy to underestimate just how much time you really need to spend. I know I significantly underedtimated how much time the size gears we need for the lathe would take to get us setup to cut. The smaller brass gearing I have cut in the past didn’t seem to take me that long to get setup for, but my memory may have gotten fuzzy.
That said, I would encourage anyone who wants to tackle a project like this. Love to see one of these work in person.
This would likely be difficult to do without DROs, but once it’s done, it’s just a JT33 taper at the top which an R8 adapter can be purchased for. The bearing is an ABEC 3 Timken 7303WN and could be somewhat expensive.
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I long for old fashioned blue prints…
I just happened to be looking at just this very thing, and came across this from NYC CNC.
So cool.
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Is someone looking for a wobble broach? I have one but with hex cutters. If you need one, let me know and maybe I can help.
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Hello Steve,
Well, as usual, I was going down the rabbit hole of “make my own tool for the job” and found a video of a guy creating a hex socket with a rotary broach. I’ll add it to the bucket list, but I think I can solve it a different way. 