This is a mod that I made to my HQ800V. However, I know for certain that this machine is made in the same factory as the Craftex B2229 sold by BusyBee in Canada and I suspect that holds true for the Grizzly G9729 (did you know that Grizzly in the US and BusyBee are owned by two brothers?), the Harbour Freight HF44142 and others of that ilk. So I think that at least some of this could be applied to those machines.
The HQ800V is the "Deluxe" model. Amongst other things, it comes with a quick-change gear box in place of the simple forward/reverse housing that most of the others come with. However, it turns out that the brochure is a tiny bit misleading -- it still comes with change gears. Yes, the gear box is useful for selecting different thread pitches, but what they don't really tell you is that you have to set it up for metric, imperial or fine feed first by swapping in some gears before the box.
Personally, I find that to be a PITA. You need two different wrenches -- one Allen key, one 13mm wrench -- to swap 3 gears. And that middle gear set (the B/C gears) in the train are the biggest PITA to refit: it's large, awkward and you have to somehow get the two bearing halves to align in the slot and get the bolt started all while working blind. Arrrgh.
Now, there's two choices for that particular position -- the 120/127 set used for all threading or the 60/127 set used for fine feeding. Gee, if there was only a 60/120/127 set, I wouldn't ever have to change it again...
Oddly enough, I happen to have a 60 tooth gear of the correct pitch lying around here. Now, what if I was to turn down the end so it was a 1 thou interference fit in the existing 120/127 and fitted a spacer in between, something like this (the gear on the right is just for illustration of the "before" state of these gears):
Then I could press them together, and maybe even fit them with some roll pins for extra security, like so:
Leaving me with something that looks like this:
Of course, the hole in the middle is now two different diameters, not to mention longer, so I need something like this, a couple of thou longer and with each diameter a couple of thou smaller than the holes so the gears can still rotate freely:
Come to think of it, now the mounting bolt is too short too. This might be a good opportunity to do some upgrades to all 4 bolts. Let's make it so I can work them all with the same wrench. How about the one for the mill column, so I don't even have to walk over to the tool box? While I'm at it, I'll bring the hard to reach one out to a suitable location:
Now, the A gear is only ever used with the 120 or 127 tooth wheels. So everything is good there, However, that 60 tooth one is now too far away for the D gear to ever reach it. Time for a longer shaft. I would have sworn I took a picture of that shaft after I made it. I was really proud of the thing -- all nicely grooved for 4mm keys and everything. However, the camera says otherwise, so you will have to settle for a scan of my working sketch instead:
Now, before anyone reading this goes running out to the shop to duplicate those measurements for their own machine, bear in mind that shaft is part of the Quick Change Gear Box and I'm certain it will be different than whatever shaft(s) are inside the more common forward/reverse box. Hell, from what I've seen, those measurements may be unique to my particular QCGB -- sometimes it seems like there's a lot of file-to-fit going on with Chinese machines. I'll illustrate that in a moment. But first, this is what you would want the end result to look like after the shaft is installed (n.b. the key is temporary. The keyway extends under that bushing and the bushing will be broached to suit when the 4mm broach I ordered finally arrives. For now I have to swap bushings and move the key to use that position):
Ok, the final arrangement is not as convenient as a couple of levers, but now it is a simple matter of loosening two set screws, swapping two gears, meshing things and tightening them down 1/2 turn. So I wouldn't call it "quick change" -- but it certainly is an "Easy Change" gear system:
Ok, this is actually slightly out of order, but let's back up a little bit to the stage where I was busy forgetting to take a picture of the shaft. That was undoubtedly because when I took the QCGB apart, I decided to correct some issues. Remember earlier when I said some things were 'file-to-fit'? I think the QCGB is one of those things. I was never happy with the way the gears meshed, primarily because the detents for the shifter were never properly located. They were not evenly spaced, so the pinion was always on one side or the other of the corresponding gear. And the #1 position was drilled too low, so there was excessive backlash in that gear. After a lot of measuring, thought and fiddling I decided the best solution was to make a new shifter, with the spring pin located to suit the #1 hole and re-work the other holes to properly centre the pinion and provide just the right backlash. Here's my new shifter fork, milled out and ready for drillng:
Oh no here it isn't? Not my fault this time, this is the forum software "Cannot add another attachment, 8 is the maximum." Ok, to be continued in the next post...
