got a little further. not overly happy with the cooling fins, still some clean up to do and drill the hole in the bottom for spark to reach cylinder, but it'll do i guess....
one thing im posting just incase it could help anyone. i needed a way stop or bump stop to controll how far in i cut each fin from outer edge to center but i didnt have one. so i took a piece of plate aluminum and a c clamp and clamped it to my slide and then in the tail stock chuck i used my led edge finder. everytime i got close i slowly advanced until it touched and the lights lit up. so that was my "stop" at least that trick worked out good. dont guess you could do that with a conventional seperate mill / lathe setup but on the combo mill/lathe that was good to have.
i have to get the push rods valve and such done before i can align the head on the cylider and drill the holes. i have already messed up one set of rocker arms. i really wish the plans would just give a radius or something on the valve striking tips of the arms but they dont. so im asking for guidence. i dont like guessing and the plans nor writtten instructions give sizes or guesses on this little tip - the curved tip that strikes the valve. or am i missing something?
If the overall thickness of the piece is .140", the radius of the curve at the end would be .070". It isn't clear, but it probably isn't critical either.
If you thin that end to .125", .156" back from the end, and file the remaining protrusion to round, I'd bet you would have a radius of .070". Don't know how you would measure that, but maybe turn a piece to .140" and compare. Or, if you know the math, calculate the radius when a chord of .156" is .015" from the arc
segment. (.140" - .125" =.015") I don't know if I ever knew how to do that.....
last night i only had a little bit of time to have fun. so i turned the pin that the rockers ride on. its a piece of 1/8 inch drill rod center drilled to a clearance fit for a piece of 2-56 all thread.
i had remembered Brian talking about drill rod usually being a bit undersized so i undersized reamed the hole in the brass post so it wouldnt be wobbly. and sure enough it was a little tight but nothing i couldnt push in with my finger so i was happy about that.
the drill rod just slide through the center hole in the pin and is held in place with a 2-56 nut on both sides. its held in the post with a set screw in the top - which is not in place yet. ill trim off the excess all thread once i have rockers in place and decide whether or not to use a washer between them and the nuts. plans dont call for one but im thinking it would be better than letting them ride against the nuts.
hope to give the rockers another shot this week. the last set has already been scrapped.
You got it backwards.--Drill rod is generally dead nuts on size. Cold rolled rod is always .0005 to .001" undersize. That is why you can't fit a 1/2" drill rod into a 1/2' bearing without sanding the o.d. a bit first.
well then my undersize reamer must be a tad bit larger than advertised then. but happily its a tight but not over tight fit. but thank you for telling me the difference . I had thought it was just the opposite.
the motor on my lathe is making a really loud jack hammering noise. at first I thought it was the head stock making it but I kept listening and moving around and decided it was coming from the motor. I put my hand on it and it and it changed the pitch a lot so that confirmed it is the motor. a couple of years ago the plastic cooling fan and slipped on the shaft and started rubbing the metal cover, I fixed that back then and checked to make sure this was not what was happening again. its not. under normal operation when you turn it off it makes sort of a ratcheting sound as it stops. this ratcheting noise is what I am hearing while running but its extremely loud now. I'm probably going to pull the motor and check it out but was wondering if anyone had any thoughts on it? its a Bolton tools at750 but its the same thing as a smithy midas 1220ltd which is who I buy my parts from instead of Bolton - smithy is really easy to work with and nice people on the phone.
but the noise is not like the fan rubbing noise was. its more of the motor shut down noise just amplified and doing it while running. ill try to get a recording of it but in the mean time any suggestions are appreciated.
At a guess I'd say it was a bearing. Hopefully it is as they're not difficult to replace and reasonably cheap (buy a good quality replacement though, not a cheap no-name brand, NSK is the best in the world, SKF is also very good).
well, i am very happy to report that after contacting smithy, even though my lathe iis actualy a bolton tools lathe of the same casting. i have learned that all my parts and anything else come from smithy now.... but back to it, they quoted the motor - which i had given explanation of why i was quoting it he replied back with a quote and then a second email with a photo and probabiliy of what was going on, which was the pully being loose. which it was and that solved the problem. long story short smithy could have used this to sell me an expensive part but chose to recomend i check this before i did. they had no reason to support my lathe but did so i will say that i really appreciate smithy for this and once i am back to a point i can email them i am going to order some parts that i caused the failure on but just havent fixed yet.
now on to build, i have started back trying to make rockers (thanks all for the tip help) i am past the milling ponit which caused the last failure where the mill dug in and took off like a climb cut. so - so far so good
Rockers pretty much done. i dont have any 2-56 shcs for the push rods to engage in so i think ill just make up something similar and thread them 2-56. one question i have is that in the drawings it says as an option in can drill "HD #40" so that i dont have to make a taper on my push rods. what its saying is to enlarge the socket of the cap screw where the push rod rides in to a #40 drill. but what i dont get is what does "HD" mean? Half Deep? heavy duty etc? and im going to look on line to see if i can find dimensions of a 2-56 shcs so i can make something to the same size with the exception of a hex socket ill just drill that #40 to what ever depth im supposed to .
another question, plans say to use "ducco" cement to glue the head on so that you can mark your holes for the head bolts. goes on to say apply some heat to set the cement. I have never used ducco cement but I do see that I can order it. can ducco cement be easily removed? or is it more of a permanent bond that is fuel resistant? id sort of like to be able to remove it once I mark my drill holes. ill use red locktite if ducco isn't removable because I can break that loose fairly easily with a pencil butain torch and then the residue usually just flakes off with my fingernail after that