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Post by 190mech on May 24, 2019 16:31:05 GMT -5
Here is a vid of a master machinist centering up a part,note the hammers in use..Adam makes it look easy,but it takes a lot longer for us rookies! www.youtube.com/watch?v=u86tX-w3Z58Perhaps you are being too gentle with the part,it needs 'bumping' to get it straight..
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Post by 90GTVert on May 24, 2019 17:34:23 GMT -5
What he's doing makes sense to me. I get that. If it were supported with room to move, "bump" it or use something like I made. The only way I can fit this in the chuck is with the spark plug hole adapter or a spark plug. I was hitting it with a brass hammer (started with a rubber mallet). It would move and that's how I got it to 0.034", but I couldn't get it better. I don't even really see how I had say 0.030" in difference there. Seems like when you hold something in an adapter like that, that's machined true, that it should clamp down tight and not really go anywhere, but however it works it moved. I dunno that I should hit this head too much harder and put all of that stress on the plug threads. This is when I do kinda wish I had a monster lathe that would just grab the whole head and I have little doubt that I could get it mounted straight at that point. Like I said, even if I had it, the 5" chuck is too shallow. The jaws aren't tall enough to support it how I'd need it because of the hose fitting sticking out on the top.
Even if I decided I'd spend the money to get gas and wire for aluminum and try to MIG it, which I think is a bad idea for a first project, I'd have to get it in the lathe somehow.
I took the chuck off, but nothing is obvious to me for a reasonable way to mount the head to the plate. Again, I'm sure this stuff is cake to the right person. I know I'm still about as noob-ish as one can get.
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Post by 190mech on May 24, 2019 18:54:54 GMT -5
Bet the plug hole is machined crooked,then a fixture plate or larger 4 jaw chuck is needed..Fixture plate could be as simple as a 1/2" bolt thru the plug hole into a large size 1/2" socket with a nut on it..Or 4 machined standoff spacers in the head bolt holes mounted on a faceplate with a long redirod run thru the plug hole,thru the spindle bore to the other end,clamping the whole mess together.. Will gladly TIG weld stuff or machine if needed to further progress on this project!
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Post by 90GTVert on May 24, 2019 19:12:01 GMT -5
Bet the plug hole is machined crooked That's what I was saying from the beginning, but I just didn't know how to deal with it. I went out right after I posted last. Looked at it. had a hair-brained idea. I shimmed a piece of aluminum and messed with it till I got it to be about 0.030" out of square when indicating on the end. Then I faced it that way. That was kinda scary, but I let it run slow. Something went wrong because when finished it came out 0.020" off instead. I may not have cut deep enough or it moved. Parted it off and I had a spacer that was flat on one end and angled on the other. Stuck that under the adapter, trying to clock it to make it's low spot align with the head's high spot, and played around for a few and it was down to ~0.014" out of square. Seems half-assed, but it almost worked.
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Post by 190mech on May 24, 2019 19:15:45 GMT -5
.014" is as good as it gets on this stuff,taking light cuts will get it back to zero!
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Post by repherence2 on May 24, 2019 20:50:57 GMT -5
I'm lost. I don't understand how an adjustable chuck would make it square unless there is adjustment in more than one axis. I could get how it would center it. I tried a shim moved around in the jaws which in my mind is a similar idea to an individually adjustable chuck, but I couldn't get anywhere that way. Maybe someday I'll figure this lathe out. EDIT : This is what I can't get. I'm sure it's not centered either, but this is where I'm stuck ATM because it's wonky this way instead of being at 90 degrees. If an adjustable chuck fixes that too, please pardon my ignorance. I was looking at 5" chucks so maybe I could hold the head in the chuck directly, but it wouldn't work anyway because the barb for the hose connection is too tall and would run into the face of the chuck. I see. to square things up, as far as squaring up the face in the chuck, I was taught to utilize the Aloris quick change tool post. I was taught to pop the Morse taper that holds the drill chuck in the tailstock. move the carriage over towards the tailstock, extend the tailstock. utilize the tailstock to square off the quick change tool post. lock it down. then slide the carriage over towards the chuck and work piece. utilizing the flat on the tool post to hold the work piece square/perpendicular, you clamp the work piece in the chuck. but looking at the pics of your qc tool post, I see that the post is small, and it does not really have enough surface area to squarely seat the face of the head against the tool post. as far as the tap-tap method of aligning, I was taught to lightly clamp the piece in the chuck (firm enough to hold the rotating piece, but not fully dogged for machining). turn the lathe on and randomly tap/hit the piece as it spins with the handle of a large (artist) paintbrush (which we normally use to brush away chips from the tool bit as we machine). the tap, method can get you pretty close. a lot of times it's that random lucky tap that gets the piece close to alignment. but that only takes care of the run out and it doesn't mean that the face will be square. aligning for Face and Periphery in a 3 jaw chuck is a big task. I will not say that it is impossible, but it is very difficult to accomplish.
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Post by repherence2 on May 25, 2019 0:58:51 GMT -5
Bet the plug hole is machined crooked That's what I was saying from the beginning, but I just didn't know how to deal with it. I went out right after I posted last. Looked at it. had a hair-brained idea. I shimmed a piece of aluminum and messed with it till I got it to be about 0.030" out of square when indicating on the end. Then I faced it that way. That was kinda scary, but I let it run slow. Something went wrong because when finished it came out 0.020" off instead. I may not have cut deep enough or it moved. Parted it off and I had a spacer that was flat on one end and angled on the other. Stuck that under the adapter, trying to clock it to make it's low spot align with the head's high spot, and played around for a few and it was down to ~0.014" out of square. Seems half-assed, but it almost worked. so after re-reading your previous posts and viewing the pics on the laptop, you are only concerned with Facing it off? if it's just facing, in that case run out would not really matter. I thought your intention was to modify the o-ring groove. I'm sorry for my misunderstanding. in your case, your only concern is the cutting the face of the head?
for that, lightly chuck the head/spark plug adapter assembly in the chuck like the picture with the dial indicator. if we index the head, let's say that the bolt hole closest to your indicator tip is 12 o'clock, and you index the tip of the dial indicator to TDC. If 12 o'clock is +0.014", I assume 6 o'clock is Zero. if such is the case, you rotate the chuck until 6 o'clock is at TDC and you tap the face of BDC until you get a reading of +0.007" with 6 o'clock at TDC. 12 to 6 o'clock is 1 axis. then you put 3 o'clock to TDC. Zero that. Sweep 180 degrees and bring 9 o'clock to TDC. lets say 9 o'clock at TDC reads +0.010". you rotate 3 o'clock to TDC and tap BDC face until you read +0.005". lets say 9 o'clock read -0.010" at TDC (3 o'clock as your Zero). you would tap BDC face (3 o'clock as indexed) until you had a reading of -0.005". 3 to 9 o'clock is another axis. you just keep checking back and forth as you start to clamp/dog it down in the 3 jaw chuck.
12 o'clock to 6 o'clock is one axis.
3 o'clock to 9 o'clock is the second axis.
the idea is to always split the difference for each axis when indicated 180 degrees out. take care of 1 axis first (ex. 12 to 6). then move on to the next axis (3 to 9 o'clock). each time you align each axis, you progressively tighten the chuck. it's a continuous process to align 2 axis with clamping points 120 degrees apart (3 jaw chuck). keep switching and checking 12-6 and 3-9. each time progressively tightening up the 3 jaw chuck until it is fully dogged firm enough to take a cut.
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Post by 90GTVert on May 25, 2019 18:04:38 GMT -5
I spent another 1-2 hours trying to get the head square in the lathe again this afternoon. I managed to get it down to 0.005" runout, then I'd knock it out thinking I could do better. Then I'd get it back... then knock it out again. Finally gave up and called 0.005" close enough. Then I faced off the entire head till I didn't see spots that were being missed (low spots like you can see in a few spots in the pic). Didn't wanna cut off anymore than I needed to for that because I had already checked the o-ring compression figures for this head long ago and it was good. Then I cut away the inner ring by the combustion chamber and cut down till I skimmed off the roof of the ex-o-ring groove. That took off some of the edge of the squish band. Because of that and the damage to the head from a wrist pin failure, I recut the squish band till it ended up 53mm diameter. I just matched the existing angle of the head by messing around with the compound rest till a cutter scored a line pretty evenly across the existing angle. If the thought of the best plan is to fill this area with a spacer, I'm going to need to go back in and flatten what once was the outer wall of the o-ring groove because it's kinda curved and I think I'd have a much easier time getting a decent fit with a flat wall there.
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Post by 90GTVert on May 26, 2019 5:24:44 GMT -5
I remembered that this isn't a 53mm bore, it's 54mm. For some reason I was thinking I had the 53. Anyway, cut the band to 54mm. Then I cut outward till I got that wall flat. Looks like I'll need to have 1.5 to 2mm aluminum for a spacer. I have 2mm sheet here, but it seems like I'd be more likely to be successful if I pick up some bar/tube large enough and try to make it on the lathe.
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Post by 90GTVert on May 26, 2019 5:37:44 GMT -5
Oh, and I was looking around and I guess I got into big LC stuff way too late. I can't find another 53 or 54mm LC kit anymore. PFS and Autotech both carried them when I last needed one, mid-late last year. Now neither has them. Hopefully I don't go through all of this and then immediately blow another wrist pin bearing apart.
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Post by 190mech on May 26, 2019 5:44:45 GMT -5
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Post by aeroxbud on May 26, 2019 7:15:24 GMT -5
Danger! Danger! Can't argue with the results though.
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Post by 90GTVert on May 26, 2019 12:45:54 GMT -5
I did it slightly different than the video. I made a holder so I could bolt on the sheet with a 7/16" bolt and washer. Seemed a little quicker/easier and I figured it would be OK for a small diameter piece like this. Here it is, almost cut. I'm sure I could have broken it off with pliers, but I thought it would be more exciting to let it come off under power. The outer section came off as one chunk and just dropped back behind the piece. The only way I managed to hurt myself was clearing off a piece of aluminum confetti and slicing my fingertip. Good news though; I made that so numb from riding 22 hours last weekend that I just saw the blood and didn't even feel it. I should prob get this checked out since now fingers on both hands go numb the more I ride or work with my hands, but I prob won't. I took it down to 2.500" diameter. Needs to be somewhere around 2.460". I needed to get off of my feet for a bit because I stepped a couple of times and the knee gave out. Between riding too much and crashing, scooters are slowly killing me. I guess it's a good way to go though. Had a question anyway. I'm thinking I should cut the OD down a little oversize for an interference fit to make it pretty solid. It's gonna be fairly thin so I know it wouldn't take much installation stress though. Good or bad idea?
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Post by 190mech on May 26, 2019 18:34:41 GMT -5
Right!Did you face the O-ring outer edge square?If so,I'd shoot for a .001-.002" interference fit and have the gasket ring thickness even with the water jacket outer sealing O-ring flange,that way the whole mess will clamp down leak free hopefully...
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Post by 90GTVert on May 26, 2019 18:38:15 GMT -5
I cut the OD down to 2.4585". The largest measurement I got from the ID of the head was 2.458". I figured that would be a minor interference fit. My logic was that I have a small piece of material that now forms part of the combustion area. Maybe it would swell more than the big chunk of material (the head), so I better not get too far off. Right or wrong? I have no idea. Then I cut the ID, starting by cutting similar to how I did the OD on the sheet metal. I tapped the center out when I could see material pushing out of the back of the cut. Finished that to 54mm. I heated the head a little and cooled the ring, then applied a few drops of Loctite retaining compound before tapping the ring into the head. Obviously that needs to be cut down. I want to figure out what needs to happen before I try that, and give the retaining compound time to set. I'm hoping the ring doesn't just fly out when I go to face it. I don't know exactly how much I should cut it down. I should be able to use off the shelf AC gaskets at this point. Some would hang over into the water jackets, but I don't think that would matter. This is assuming I can get proper squish clearnnce. So I'm guessing I need to cut out basically what the gasket thickness is, or a little less for compression. That makes this seem really "iffy" if so, because if I shave say 0.5mm off of the sealing surface, then I've got IIRC 0.5-0.6mm of that spacer left and the lip on the head when it's all done.
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