mills 1.3cc diesel engine crankshaft bushes mikes-models

session 1 - 22nd March 2008 crankcase/shaft bushes

After completing the crankcase and backplate the next task is to make the
two bushes that ill carry the crankshaft. Ron says that there are two methods
of bushing the crankcase to consider. Firstly the two bushes approach,
where one is fitted from the front of the engine and the second from inside
the crankcase. The second is by making just one long bush.

I have decided to make the two bush version as it has the advantage of a
small oil reservoir in the centre of the tapered front of the crankcase.

As I discovered there is one important misprint in the description. The
hole in the bushes should be reamed 7/32nd and not 9/32nd as mentioned
in the article. Perhaps more importantly though is the incorrect hand
reamer size given at the beginning of the section of the article. It should be
7/32nd so if you have to buy one (as I did) make sure you buy the right one!

After putting the phosphur bronze bar in the 3 jaw chuck I faced the end,
then centre drilled and followed with a small drill to drill the pilot hole. Here I
learn't another lesson, phosphur bronze is a grabbing type metal for I broke
my first drill in a very long time. I wasn't feeding it very heavily but broke it
did. So now in addition to the 7/32nd hand reamer I need to buy, I will have
to replace the broken drill........

That seemed to be the right time to call it a day!

Time taken on this part 20 minutes.
Total time 40 hours 50 minutes.

session 2 - 22nd April 2008

Its a surprise to me, to see that it is a whole month since I did any work on
the bushes!

Today I faced off the bar stock then centre drilled it ready for drilling the
?/64th" drill. Since I broke my a drill on my fisrt attempt, I decided to drill the
hole straight away using the ?/64" drill which I did to a depth of 1" to allow
sufficient for any adjustments.

It was just as well I did because when turning down ready for a close fit to
the crankcase, I went a couple of thou too far, and whilst the bush may have
worked, I decided to do another with a slightly tighter fit.

Once I turned the bar to diameter for the required diameter I then followed
the article where Ron takes a further 2 thou off in the centre, to allow for the
Loctite adhesive [photo 1 on the left].

I then turned the outside of the as yet, unmade flange to the required 0.400"
before carefully parting off. I then reveresed the bush in the chuck and faced
the flange to the required dimension as shown on the plans.

The next task to complete, was to ream the hole 7/32nd" with my new
reamer. I found that it was better to operate the lathe under power at is
slowest speed than by hand, which is an advantage with the new lathes
variable speed control.

The reamer was used with cutting oil and it soon clogged up [photo 2 on the
right]. I only know this as I decided to take it slowly, and was rewarded by a
better finish. In all I must have withdrawn the reamer perhaps four times
before finally exiting the bush.

That completed the first bush of the two required and a trial fit [photo 3 on
the left] seemed fine. I have the other bush to make but this one needs a slot
cut into the front face.

This was about as much as I could physically do today so I stopped before I
made any mistakes.

All in all quite a good short session and a real pleasure to get make to the
Mills.

Time taken on this part 30 minutes.
Total time 41 hours 20 minutes.

Session 3 - 24th April 2008

The second bush was a lot easier to make, not only because I have made one
already but I could use the second as a quick reference when machining
today's. The only difference was the slot that had to be cut in the front face.

It should have been 1/32" wide but as the smallest end mill I have is 1/16th I
used that. I can't see it being a major problem as it only serves as an oil
reservoir as far as I can see, so I made it slightly shallower than the plan asks
for.

I used my pin vice [photo 4 on the right] for the first time. It was a present for
Christmas just past. I needed to clean up the groove and because of its small
size held it in the hand held vice. I was very impressed, it certainly helped.

Well thats the two bushes made so its back to the cylinder liner next. I am
looking forward to making it, time however will tell.

Time taken on this part 20 minutes.
Total time 41 hours 40 minutes.

Fin.