Yesterday I managed to make the tappets for one engine (8 in all) and they are now awaiting my first attempt at case hardening. To speed up their production I made a tube out of stainless steel to fit over the slot drill I was using. The method worked fine and it didn't take too long to make. However, today I only managed a short time in the workshop and looked at how to cut the chamber in the valve guides with the radius required at there base. I did try and make a special tool out of some drill rod (as the Americans call it) but whilst they worked to a degree I wasn't happy.
That's when my memory kicked in and I remembered the ball nose cutters I have and one was in the correct size of 0.250". A quick check of the radius showed it to be near enough so my previously turned valve guide was mounted in the chuck and when considering how to get to depth the second part of my memory decided to wake up. I have a clamp that I attach to the tailstock and then use a DTI, secured to a small magnetic base, to rest against the clamp so ensuring complete accuracy with depth. Why I didn't use it yesterday for the tappets I do not know!!!
I did not use the ball nose milling cutter directly on the valve guide but drilled it out first just undersized and using the cutter to clean up and cut the bottom radius.
Another plan issue showed itself yesterday when completing the two camshaft bushes. Neither the article or the plans show the angle of the oil holes required in both bushes. Nor does it give the diameter of the hole.
My solution was to use the new digital angle ruler bought from Axminster tools on the plan (see photo). This gave a reading of 33 degrees and measuring the plan showed the hole size o be 1/16". I had a bit of a blonde moment however when working out how best to drill the hole and its chamfered entrance. I thought the best was would be to use my Proxxon drill and stand. So I set the head over to 33 degrees and yes I know you will know but when depressing the stand of course it goes only directly up and down!
Blushing I got out my angle vice and after setting the digital angle meter to zero on the base of the drill stand, I adjusted the vice to the required angle and form then on it was simple.
The next session should see most of the valve guides for this first engine completed. After that as soon as the 1.8mm drills arrive I can complete the two nuts required for each valve before carrying out a new experience for me, case hardening the tappets and nuts. I will cover the experience in a separate section of the website as I have had some advice from a member of the forum I use.
If you don't know it then I can highly recommend the Home Model Engine Machinist forum, especially if you are a novice as they are both approachable and knowledgeable.
As always here are a few photo's that may help explain my ramblings.....
- Only place to find the angle of the oil holes – with my digital angle rulers!
- Stupid or what! I expected this to work – until I pulled the handle!
- Setting the correct angle with my digital angle meter.
- Tube cut to ensure all tappets bored to same depth
- The two valve guides made so far – one bored out the other a blank.
- Tappets, valves, camshaft bushes and one valve guide
- The main parts made so far for one Seal engine.






