2016 POTD Thread Archive

In keeping with the " I made a rackIMG_1232.JPG " theme, I am almost done re-purposing a rack that came from an in home oxygen delivery truck. The tubes are 5" diameter and 24" long. All the stock I have that is longer ( 5' lengths ) are stored out in the shed. I also discovered that I have WAY TOO MUCH FORGED 4140 , this is air brake cam shaft and there is close to 100' of 1 1/2" and 1 1/4" going back to the scrap steel bin at work.
 
I made a replacement knob for a swiveling vise today. Bought this off eBay and didn’t notice that the clamp knob was broken.

I disassembled the clamp screw, it was a M10 x 1.5 mm thread. I have the proper die, but decided to single-point thread a new clamp screw from CRS. I love the universal gear box on my Grizzly G0709 lathe; flip one knob to change between imperial and metric threads. It would have been a lot quicker to just run a die over the rod, but I like refreshing myself on the basics. As luck would have it, I had my compound set at 45 deg. for the first pass! After that was corrected, the threading went well. Used an M10 nut to check the thread size, took 0.002” to 0.004” per pass.

The new knob was made from a 2” aluminum round turned down to 1 ½”. I don’t have a radius turning attachment so both sides of the knob were tapered at 10 deg. Here’s one thing I don’t like about the Grizzly G0709 lathe, the compound protractor doesn’t go a full 360 deg., just 120 deg. I used a 1-2-3 block on the side of the cross slide and a 10 deg. tapered gauge block on the compound to set the angle.

It would have been easier to just knurl the knob OD, but I went with 10 finger notches (probably not the technical term) around the OD instead. Circumference of a 1 ½” circle is 4.17”, so each radial division is 0.417”. I went with a 5/16” (0.3125”) end mill to half-depth to leave just over 0.100” between the notches. The indexing was done with a dividing head, easy math for 10 divisions (40 turns per 360 deg.). A bit of afterthought on my part, I could of used the points on a circle function (whatever the function is called) on my mTech DRO to do each hole, but went the dividing head/chuck route.

The knob was tapped M10 x 1.5 and a 10-24 set screw added to lock it to the screw. Works great though in retrospect the edges of the finger notches are a little sharp at a near 90 deg. angle. If I ever make another I'd go with a 1/2" or larger end mill to reduce the angle. Great to spend 3 hours making a part for a $30 vise!

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I've just had to get a third blower housing, and it took extra effort to find just the housing, as Gravely has decided now that the mower is a couple of years old, if you need a new housing, you also need to buy all the bits and pieces that go inside the housing as well [which adds several hundred dollars to the cost, yay].

Anyway, the housing gets wrecked because something other than grass gets sucked in, such as a branch or occasionally a rock, and if the object goes through at just the right angle, it gets wedged between the fan and the housing, and since the housing is plastic, the fan pushes the object through the housing. This is the picture of the damaged housing:
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Here's the shield and the new housing:
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This is the fan assembly. The tips of each blade are all curved backwards, even after I welded braces to each one, and worn so they are sharp. I think I need to buy or make another blade assembly with thicker blades [or at least thicker tips], as they are only maybe 5/32" or so thick mild steel.
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The finished assembly. It's also been previously been modified so the housing is less of a structural member, by adding that metal bar to hold the idler wheel assembly to the mounting bracket, as well as internally an bent plate to connect the inside bearing to pulley assembly, as the original housing failed at both the inside bearing [directly behind that black pulley] and at each end of the mounting bracket [originally, all the weight of the blower assembly transfers to the lawn mower via 2 bolts through the plastic housing at each end of the mounting bracket]. Now the point of failure for the assembly seems to be the bolts on the mower deck [they go through the holes at each end of the mounting bracket].
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Tomorrow, I see how it works.

The shield does add significantly to the weight of the assembly, I may have to make another shield from 3/32" or 14 gauge steel instead to lose some weight.
 
the saga of my new countershaft project continues. I'm converting the motor belt from V to poly-v so I can use the original flywheel on the treadmill motor for a bunch of different reasons. However, the original pulley that went on the end of one of the treadmill rollers has a large bore, so I need to make a hub to fit it and go on the end of the 1/2in countershaft.

Made a hub out of a piece of random steel, turned it true on the countershaft and stupidly misread the micrometer and turned it 1mm undersize :( As a bodge, I turned the rest of the hub down to the right size, pressed on the pulley but now the pulley interferes with the countershaft bracket. Bugger
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so, I ruminate on this overnight and come up with the idea of turning down the hub, pressing on a ring of steel and then turning that down to the right OD. Find another piece of scrap (about 2 1/4in OD), whip out the hacksaw, cut off a chunk, face it both sides and then trepan 1/2in through one side. Plan was to flip it round and trepan through from the other side. There'd still be a ton of cutting to get that down to the right OD once I pressed it on.
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then, while hugging the wife at some point (not that kind of hugging, she was feeling sad about me not getting a job I was hoping for) I had one of my random light bulb moments and remembered that I kept the rollers from the treadmill. Tada!
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cut off the end (not shown), faced it and measured VERY CAREFULLY the ID. Now I need to do far less work to turn down the hub OD to press the sleeve on.

set up of the countershaft to mount the hub and turn down the OD. This has to be as true to the axis of the countershaft as possible to reduce the chance of vibrations. Here the shaft is gripped by the last 3/8in of the shaft and trued in the 4 jaw to less than 0.001 run out. Then the steady is mounted and the countershaft trued in that, ideally to 0.001 or less. After that the pulley is mounted, set screws tightened and the cutting can begin. Better not screw it up again or I'll be really ****** with myself!
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Didn't think to take pictures while I was working, but here are pictures of the finished product.
Made from 1in aluminum stock on a grizzly G0765.

Didn't plan anything, just chucked it up, indicated and turned.

Drilled out the bottom spindle and added a ball bearing with some loctite 609.

For the finish I started with coarse medium and fine Emery paper, then went from 320 to 2000 grit paper.

Best run time so far is 1 min 45 sec, which is decent. I think AI is to light for a spinning top. I can get 3 min runtime from another top I machined in brass.

Thanks for taking a look.

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Sent from my XT1097 using Tapatalk

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Did not get any pictures and did not machine anything, but pulled out my forge and took a 5/8 bar and made a new latch for my gate. The old one was a piece of 5/8 pipe that they punched square holes in, and it broke off at the front edge of the holes. Well, I used 5/8 bar, flattened out, then made the correct bends to match what was needed. Once finished I did a quick blackening with old oil, and mounted it.
also finished up my PM#7 steam engine
 
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