www.mikes-models.com blog

I needed to have a method of sanding in an awkward narrow square hole. Whilst visiting my local do it yourself  store looking for some child safe paint (see my blog about spraying and making a box for my Granddaughter) I spotted the Black and Decker Mouse sander and saw it came with a small nose extension piece that seemed ideal.

Whilst I may well have bought it cheaper elsewhere I picked one up as the need was for a solution now. The sander is a nice fit when working with the main sanding papers but I found it more awkward when using just the nose extension piece, but to be fair that my have just been the position I needed to be in when sanding the square hole.

Its performance however, was excellent and I could not have managed to sand the square without the mouse sander. Also I like the way they have produced the main sanding sheets with two outside tabs. These when removed are used to replace the nose part of the sanding body so extending greatly the durability of sanding time since the nose area can get greater use than the main body at times. So well done for that nice little touch.

Overall for £27.99, the sander is good value for money and a very versatile tool for small scale sanding, exactly what I wanted. I have no doubt it will prove very useful over the coming years.

Not a lot of work this week in the workshop on the Seal engines due to working in part on some wooden toy's for my new Grand child Freya (and I hate wood!). However it has given me time to reflect on the quality of work undertaken January last year and I have decided to replace the Seal block and start again. Whilst it may be a little drastic I think it is the right thing to do and for £38 for a new one from Hemingway's its not worth trying to adjust/bodge/amend the existing one. It will also allow me to 'experiment' with the placing of studs and error where two studs try to share the same hole!

My reason for replacing is the poor alignment I made when boring the seating s for the valve inserts and really came to light when inspecting it for the first time in over 18 months. On a positive note my skill level must have improved (it couldn't have been worse!) as shown with the second and later casting for the other engine.

Whilst talking to Kirk Burwell (very approachable man)from Hemingway's about the handing of timing cover and backplate castings Kirk confirmed these do not exist and suspects its because there isn't a lot of call for them so it looks like I shall be doing a little pattern making in the near future!

I am hoping that next week I can return to metal work instead of wood! However time always seems to be less available than the projects to be done. Watch this space!

In happier times -before cutting the seats for the valves poorly.

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.....

Today I managed a session in the workshop and completed (other than cutting a screwdriver slot in the valve faces) the first set of 8 valves. Last night I thought I would change my plan and get something to revolve to spur me on! To that end I ma going to get the valve side completed i.e. the camshaft fitted and working on one engine. To that end I drew up machining methods for the tappets, nuts, valve inserts, and camshaft bearings so that side of the engine works!

So after completing the valves the next items I was going to tackle was the two 1/4" hex nuts per valve. That was until I found I didn't have a suitable drill for the tapping. According to my charts I needed a 1.8mm No. 50 or 0.0709" drill. When going to my numbers drill box the only one missing is ............yep No. 50. So that job was put to one side and instead I decided to make the two camshaft bushes. The first went well enough and was reamed 0.250" and was pleased when it fits the camshaft nicely.

The second bush however produced another problem when checking the main block casting. This one was bought second and had some work done by the previous owner. All the work when checked previously was of a high standard, however the two holes bored previously were not the same. One, the timing end was spot on but the second was slightly oval! So worked stopped on the bush because it will need to be oversized, and the casting set up on my angle plate on the mill and the hole bored circular. When the finished 'round' hole was measured the bush will need to be some 35 thou oversize.

I can't see this will cause any problems yet, but will keep my fingers crossed.  I will be using some hardening powder for both the nuts and the tappets, for the first time so that will be interesting. I have had it for a couple of years now and never used it before so if anyone has any tips additional to the 'normal' instructions I have, that would be very helpful.

I managed a short session today and managed to nearly complete the first engines 8 valves. There only remains 4 valves to be finished to overall size then cut a slot in each face. When these 8 are done I will then make the corresponding valve guides. I am undecided whether to follow this by drilling and tapping the top stud holes followed by inserting the cylinders, valve guides and facing off.

My reason for being in two minds is an itch to work on the Fowler tender, but the valves and guides have to be completed first. Watch this space.

I thought I would share with you how I am making the valves for the Seal engine design by Edgar T Westbury. Sadly I am a 'list man' and after working through my first machining method list it was amended yet again in the light of experience. Having completed 5 now I believe I have now tied it down reasonably well.

I have the list alongside the lathe as an aide memoir and it goes like:-

1. Face off the stainless steel bar and then centre drill for the tailstock centre.

2. Extend the bar 1.75" away from the chuck and lubricate end for the half centre.

3. Using DRO scribe line 0.25" from tailstock end.

4. Using HSS tool steel (ground to cut from left to right) turn down the required 0.250 long valve end stem to the diameter of 0.0709" (I round to 0.071") for 8BA threading in phase 2. (Should now be as picture 1).

5. Change tool to one that cuts from right to left and set it against the face of bar (the 0.071" diameter) and set DRO to 0.000.

6. Using DRO scribe lines for length if Stem, length of taper cut (45 deg), and overall length of valve. These marks only serve as checks whilst machining the rest of the valve.

7. Turn down diameter to the finished valve head size for length of the bar (using the DRO and scribe marks made in 6 above. (Should now be as per picture 2).

8. Now turn down to main valve Stem diameter (picture 3).

9. Using DRO, re scribe the marks for the taper to cut and end of valve before cutting the 45 degree face (picture 4).

10 Change the tool for parting off  and checking with the DRO part off the valve (leaving the oversized bar at the valve stem end.

11. Hold valve in vice by stem end and use Proxxon to cut the valve off.

This completes the first phase and what I call a 'valve blank'.  The second phase requires the valve blank to be placed into a home made collet, allowing the threading of the stem to 8BA for 0.250" .

The final stage is to measure the length of valve so the amount to be removed when facing the valve off can be ascertained.

Now all you have to do is repeat the process another 15 times (plus the ones you mess up....and that can be quite a few with me!) plus a couple of spares for the future.

As a meerkat once said...'simples'

Well today's session I should have made at least 4 valves. In the end silly errors resulted in two being scrapped before finishing. On the plus side the work I did whilst laid down yesterday afternoon, in writing up an aide memoir for machining, worked well.

I decided after completing the first valve proper, that I would treat their manufacture in two phases. The first was to do all the turning on the lathe whilst the second is to thread the end of the valve stems 8BA. The second phase will be to face the valves off to finished size.

Based on today's work rate it will take at least another 4 sessions and some more stainless steel stock! Still more made than I had yesterday.......

Spent the last couple of days working on a couple of wood (Grrrrr!!!!) projects for my first granddaughter. The first was a wooden type puzzle freely available for a few pounds. However I decided to make one more individual instead.

My material choice was plywood and I did a lot of research into safe paints and finishes since everything at the moment gravitates to Freya's mouth!

I won't go into the why's and wherefores of how I made the puzzle suffice to say I did enjoy making the aluminium buttons for it the most. I sorted out a system fairly quickly to manufacture 12 of then buttons and was amazed to finish them in one session, without a single fault,  and for me that's a massive achievement. Indeed it could be a first!

Once I had finished the wooden puzzle I finished off a spinning top I had been making. If you want to read more about the spinning top (very addictive in the trial runs to make sure it worked - and again and again...)then visit my pen making website to read more.

Hopeful that tomorrow I will be recommencing work on the 16 valves I need to make for the pair of Seal engines. Perhaps I can bring a bit of  the luck I had making the buttons?

Yesterday was a difficult day. I was really pleased with my first valve and took a lot of time over it! Yesterday I ruined it. Ok, it was always going to be a test piece to sort out the machining stages, but I had hoped it would survive after so many chances to ruin it.

Where did I go wrong? Or, where were the problems discovered if I want to be positive. Well the reduction in length to finished size went well to 1/2 a thou (how accurate can we measure with the tools available to model engineers?) and facing the valve to finished depth also was achieved with the little fixture I made. So the process is now set for the production run. So how did it go wrong?

Looking at the plans I have found yet another error! and one that has **&^^%^&* me off. The write up in Edgar's article brought no comfort on his brief description on making the valves and his plan shows the wrong size BA thread! It reads 8BA and the diameter for cutting 8BA according to British fasteners is 0.086" and the plans shows only one diameter of valve stem, 3/32nd" or 0.09367" a difference of nearly 8 thousandths of an inch!

So when I decided to finish the valve by threading the end it was obviously much too large. With previous experience I know the plans are riddled with errors so I thought it must be perhaps 6BA instead. It was over to the books to find out what BA size came nearest 3/32nd". In the publications there are many data tables and drill sizes for tapping threads but little or no data for threading (well not in my books) however a quick search on the internet found the size of 7 BA nearest but the valve stem was 0.00445"  under 7BA. If we go to a thread that is under the stem diameter (and as stated on the plans) then a further 0.00775" need to be removed. This also does not account for a further reduction of between 5 and 10% recommended in some of the literature to stop pushing metal in front of the cut.

Perhaps I should have seen it and checked but I think that the plan should show the reduction in stem diameter, shouldn't it? Another wind up point is the length of the thread is not shown either on the plan or in the article! Measuring against the plan shows it near to 0.250" so that's the plan and I will try the next one with a 1/4" end reduction.

On the positive side I  made a suitable collet for holding the valve in the chuck for facing and bring it to finished size. After the messing about with the first valve I decided to make the final collet in brass for durability.