| The Craftmans Shop > New from Old |
| 4x6 Rebuild |
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| Neil74:
Have you any marine salvage yards nearby? I generally pick up used propeller shafts cheap, most are damaged and none usable but very good source of cheap naval bronze and sometimes monel shafts also. I have gotten 3 to 5foot lentghs of .625in to 3 inch diameter shafts. |
| sparky961:
I was at this again recently and took some pictures while working on things. I was thinking "hey, I should post a short writeup on this" but then it occurred that I already started a thread on it! Wow, memory don't fail me now! So I ended off last time saying that I spent a lot of time working on the blade guides and I might have some pictures.... At last, here we go: Rough cutting just shy of the layout lines. Safety here might be a tad questionable, but I had my hands braced in such a way that I was unlikely to slip into the blade. The chunk of steel gets hot while doing this, but DO NOT FOR ANY REASON WEAR GLOVES AT THE SAW! I swapped between the two I was making once one got too hot to handle. Especially with most of our small machines, I have learned to value my bandsaw over any other tool to save time in removing large amounts of waste material. In this case, I even still have the chunks that were cut away for another project some other day! Pictures of the milling operations weren't great, as I was spending all of my time thinking and cranking. Most of the cutting was done at very shallow depth and slow feed due to my machine & setup's complete lack of rigidity. Back to the bandsaw to reveal more of the part within! Alas it's starting to look like the CAD model! Once again on the mill to cut the groove in the back. The slot for the bolt and guide bearing was cut using two setups. Skipped a few steps and pictures, but here it is mounted on the saw with bearings and all: This setup should be looking familiar by now. It's how I use my rotary table most of the time. But there's a bit of a twist this time. I have the rotary table angled down by 5 degrees to account for the lead of the worm gear. I would probably try something a bit more stable next time, but this didn't move despite the single-point hammering away. It's hard to get it up high enough so that the spindle reaches far enough to cut while keeping everything nice and rigid. Nature of the beast, I suppose... and I grudgingly live with it until I have space/money/time for a better setup. To help out a bit, I made up a very rigid single point gear cutting tool. It's like a fly cutter but the tool is perpendicular to the spindle - not sure what the name would be. I hand ground the tool bit using the old gear as a checking gauge. After a bit of stoning we're off to the the races. Material was generously donated by a friend of a friend - some sort of very expensive looking bronze. I had made up the blank and arbour a few months ago and didn't take photos - pretty standard stuff there. ;) I was going to make one out of aluminum too and use it to verify the setup, but that just didn't happen. Dividing using the rotary table was simple because 20 teeth means all even numbers. I should note too that the first time around I cut to the full depth I thought would be correct. Slow and steady and it cut nicely albeit very noisily. Skipping ahead a few chapters, I ended up re-mounting this and cutting around the whole thing 2 more times before it fit. Two things I did right, though not on purpose: Don't tear down the setup before checking the part, and when making a difficult one-off part cut small, check fit, cut a bit more, repeat. Making the last cut - WOO HOO! (hours passed between the two shots) Mostly done, just needs hole cross-drilled for a roll pin and a keyway cut. After checking the fit, I found the gears were way too tight. I could turn them by hand with considerable force but after re-cutting them multiple times I was worried it would become too loose if I did another machining pass. So, a bit of thinking and a bit of reckless caution thrown into the wind and I decided to run them in - using something like what may have been in there originally, OIL AND GRIT. Now, generally you don't want to be throwing sand into the running gearbox of any machinery but let me tell you the process worked FANTASTICALLY! I used a haphazard combination of chainsaw oil, 10W30, penetrating fluid, granite dust, and some of the aluminum oxide and silicon carbide dust swept up from around my grinder. If you saw my thread on the repulsion motor (http://madmodder.net/index.php?topic=6574.msg70005#msg70005) the next picture might make more sense. Really, I didn't know I had a motor that turned the right way. I just needed to make it turn and it was getting very late! The gears got a bit hot while it was doing it's thing, but they ran in to a nice fit with very little resistance. At this stage the gear is just held on the shaft with a light friction fit. It didn't slip while I did this, otherwise I would have had to put in the keyway and/or roll pin first. Let's just say I was excited to see them turning together. :) After all of that crazy fun, I did a thorough cleaning and covered the openings with duct tape to keep them clean. Still left to do is to finish the gear details and then I have some ideas for this mess... If you look carefully, you'll see that someone has broken off the right bearing and replaced it (farmer style) with a nut. Well, that's all I have for now. We'll see how many months before I update this thread again. Thanks for your interest! -Sparky |
| -steves-:
Thats really cool :thumbup: |
| krv3000:
HI nicely dun keep at it |
| sparky961:
Thanks for the encouragement gents. It turns out this project has been doing a surprisingly good job of holding my interest! Here are some more pictures and comments in the continuing saga... My plan is to completely replace the pivot bearings, so the first step? Out with the old... First question, how the heck do I hold it? The bandsaw base is almost the same size as the base of my machine! Here's where the inspiration from Ade's huge block of aluminum comes into play. I shall make it fit!!! In the picture above, it hangs off the front quite a bit and causes the carriage to slide with increased effort. I wouldn't want to use the machine like this all the time but I think this small abuse should be ok. After quite a few passes with the fly cutter, I'm rewarded with a shiny swath the entire length of the part. In retrospect, after zip cutting the old ears off I should have ground the stumps down further to make the machining go quicker. Oh well, lesson learned... cast iron machines quick enough anyway. (edit) I should probably add a "do as I say, not as I do" here, and mention that might not be a good idea to use a drill chuck for fly cutting. I know this, but sometimes I need to get more length on my tooling because I have no adjustable knee or column, just the spindle and it's minimal travel (/edit) Oh, I do love the look of a fly cut surface! Except for the remnants of the tapped hole in the back and a small casting defect that was revealed, the surface is shiny, smooth and consistent. While it was still playing piggyback with my machine, I laid out a hole pattern for where the new ones will be going. This took a bit of thought because I had to take the thickness of the casting sides and make sure there was enough room for bolt heads underneath. I didn't take a picture of the setup, but after I was all done with the top side, I flipped the whole thing over and used a similar setup to bolt it down. I carefully milled a round "land" for each bolt head - required because of the casting's sloped inner surfaces. I didn't take pictures of making the new ears, but it was pretty straight forward. I used 3/4" x 2" HR bar, 1018 or 1045 I think, saw cut to length and then milled off the chamfers while holding at a 45 degree angle in a milling vice. Two M8 x 1.25 holes were drilled & tapped in the bottom to correspond with the mounting holes drilled in the saw base. The pivot hole was drilled shy of 5/8 then reamed to final size. An oil-lite bushing was then pushed in using the bench vise and back to the mill once more for a quick 1/2" ream to size (required because the thin bushing closes in very easily on the inside, even with a light press fit). I installed the bolts loosely and inserted the 1/2" shaft, then pushing both to the front of the mounting hole to get pretty good alignment with the holes, tightened them down. I must have done something right because there was no play in the shaft yet with very light tapping it slides through the bushings without binding. Since I'm going the distance with this rebuild, I'm thinking I'll design a new stand to replace the all-too-common flimsy sheet metal one. I've seen a few other designs, but so far none of those has captured my interest. I'll have to go through them again and see what I come up with. -Sparky |
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