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.

Well I managed to get back into the workshop this morning and decided that I would start on the last camshaft for the Seal engine since the lathe was still set up for the cam turning fixture. With the half turned practice blank that will make nearly 4 camshafts now made. Two proper camshafts made from Stainless Steel and another made from BMS which I intend to try and harden. If it works I may use it as a comparator in one of the engines. If it doesn't work, well I will have learnt from that as well.

I am going to write a large lettered poster for the workshop saying “If it looks or feels wrong then it IS! Investigate as to why before continuing!”  I may produce a dozen copies and post them all around the workshop and maybe have it tattooed to the inside of my eyelids as well.

I did have a few set up problems with the camshaft fixture turning true. I must be learning something though because it took me less time than usual to find the culprit. My tail stock also swivels around the locking point located centrally. I couldn't see to begin with why, when I was off setting the tail stock, the live centre did not follow, indeed it was going the other way! It was only when I lent on it that it revolved! Doh.

Hopefully tomorrow I shall complete the camshaft and then I can get my lathe back.

Well another lesson learned and mystery solved. It brought to mind all the times when 'something' wasn't right and in the past I have not investigated fully. Its only since the rebuild of the Myford ML7 that I have been far more investigative with good benefits resulting. So the new motto will hopefully serve to 'help' me. Time will tell.

Today I managed to finish turning the second camshaft as can be seen in the photo below although I have yet to complete cleaning up the camshaft. It is only held in the chuck to allow it to be filed and sanded. It is not unsupported for turning, just using the Myford as a very expensive vice!

The second camshaft took a lot less time than the first, but I did annoyingly catch one of the lobes with a nick. I blame SWMBO who came in at a very inopportune time! I managed to keep my muttering under my breath until she left. Then I said a loud tut tut. Fortunately most of the mark was removed with further cutting but part of it is still there, and I know its still there!

Hopefully tomorrow will see an end to cam cutting for a little while, although I still have one more to make. At least I now have a pair of camshafts and that should allow me to tackle the main castingsnext , namely the cylinder blocks. Anyway here is the photo of the latest camshaft, half way through tidying up.

Having completed the first Seal camshaft you can imagine my bitter disappointment when checking the profiles against the plans to find that they were miles out! No matter how many times I looked at them, turned them around and even when stood on my head, it wasn’t right!

I rechecked the methodology; re read Steve Huck’s article, to find out where I went wrong but all to no avail. The camshaft looked nice, but looking nice was not going to cut the mustard for a successful engine build, let alone the two Seal engines I am making!

When I couldn’t make any further progress in finding the answer I emailed Steve Huck and after many, many, emails, photo’s and explanations we came to find the answer.

Steve makes it perfectly clear in his article (reproduced on this website, by kind permission of Steve) that when making the cuts you turn the camshaft 5 degrees AWAY from you, i.e. clockwise. So what did I do? Well I thought that moving the cam 5 degrees towards me would make an easier cut and my 360 degree wheel had two scales on it (see photo). So when I made the 270 degree cut I should in fact have been making the 90 degree cut! So in fact I was 180 degrees out.

To make sure no one else makes the same mistake Steve has amended his cutting chart (see downloads) including a portion of the 360 degree wheel he uses, and makes it even clearer that the cut must be AWAY from you. Not that he didn’t say it clear enough in his article, no the fault was all mine. You may think this shows me up more than a little, well you would be incorrect to think such a thing.

Indeed it only goes to show my genius! Why? Well the two engines I am building will run contrary to each other so one needs in fact to run backwards. When analysing the pattern I had achieved Steve emailed me to say that the camshaft I had made was exactly what was needed to run an engine in the opposite direction.

So in fact what you may think of as a mistake was in fact planned on my part………….. to make the second engine  work…….tee hee…

So now I can make the two ‘proper’ camshafts with confidence. After all the research, and with the help of Steve to find out what happened to produce my ‘special’ camshaft, I have a far better understanding of a subject I thought I knew something about…….In the end, a good outcome.

As previous readers of my blog will know I am building 2 Seal engines and am making the Cams at the moment. However, can someone please clear up some confusion for me.

 1. Is the cam profiles on the published plan correct?

2. What is your understanding on the firing order for the profiles shown on the plan? 

I am aware that the firing order was changed in the Aug 1947 magazine to 1, 3, 4, 2. rather than the order shown under the cams in the photo, however should the profiles also have changed?

 I have seen two photo's of completed plans that seem to match the plans profiles, and I want to confirm the firing order. An early reply would be very much appreciated.

Also If anyone has any comment about how the engines should be handed or built so they will power the boat with two contra rotaing props that would also be helpful.

Kind regards

Mike

Well other than loosing an hour because of British Summer time, and watching Jensen Button win the Oz GP (well done to both Jensen and Lewis Hamilton for a great drive in a poor car - amazing from McLaren!)at 0600 hours, I managed to get out into the workshop for a second successive day! Brilliant.......

Onto the build though........ I managed to get both stainless steel camhaft taper and threaded ends done, and also cut out the blank cams completing one piece. So tomorrow I hope to complete the cutting of the cam blanks out of the second. Completing this phase before profile cutting the cams. The second photo below shows where I got to before stopping for the day .....ignore the left hand side of the shafts since they have yet to be cut to final size. Also there will be a cross drilled hole in the left hand side to accommodate Steve Huck's idea of a marker when I profile the cams.

When the camshafts are finished to size the left hand side is much reduced (and loosing the cross drilled hole).

I think that when I have managed to make the cams that will be a big psychological problem over. The next 'big' job will be the crankshafts but I may have a go at bringing the castings to size first before making the crankshafts. After that its all down hill! Only 16 valves, 8 cylinder liners, 8 conrods, 8 pistons................oh *&^%% hell what have I done!!!!!

28^th March 2009

Well today was a good day. The first of many I hope. I wanted to complete at least one blank camshaft in steel. I expect I could have made 1 ½ blanks if I hadn’t made a mistake with the taper end of the camshaft.

I had completed all the fussy bits and then took too much off the 1/8^th”  tail. So that was parted off and will be kept as a comparator piece (scrap really!). I was a little miffed that I managed to get all the parts within 0.001” only to make a silly mistake at the end (literally).

At least the structure I put so much time into for machining seemed to work. Indeed the time I took to make the nearly completed camshaft blank [see photo] was much reduced for the second attempt. This particular camshaft is made from BMS (bright metal steel) and will be for my hardening experiment. I have another two blanks to make over the next couple of days but these will be turned from stainless steel. Not sure if it’s the best material but it is surely harder wearing than BMS.

The only task remaining to complete today’s example is to drill the small hole in the opposite end from the taper. This is to allow a small steel pointer to be used when turning the camshaft in the fixture designed by Steve Huck (thanks again Steve!). I will drill the hole when I have all three blanks machined to the same point to make use of the set up time involved.

I decided that the best way to approach the task of producing the cam blank was to machine the awkward part first. The first job was to centre the bar in the 4 jaw chuck with the minimum showing. Then the bar was turned down first to 0.250” diameter. Using the digital readouts the start and end of the taper was lightly scored on to the bar, along with the measurement of the length for the thread.

It was then another turning job to bring the diameter down to suit the 2BA thread which was then threaded by use of the die held in the tailstock holder. Once this was carried out the thread was then reduced to size. The next procedure was to turn the 10° taper just in time noticing that the tap setting should be only 5°. I must admit to a little apprehension when sizing the job up especially blending the taper to the threads. In the end though there wasn’t any difficulty and the thought was far worse than the deed (as I have found with many engineering tasks done for the first time).

Once the tapered end was completed the 4 jaws were released and the bar drawn out, centered again, and then parted off with sufficient length to make a complete camshaft blank.

The bar was reversed in the 4 jaw with only enough bar showing to allow the dti to be used to centre the bar. After facing off the end was centre drilled so a live centre could be used in the production of the camshaft. This was the first time that I thought about how I was going to turn the cams in the next stage. In particular because the taper end was very small and certainly too small to centre drill and use against the live centre, but likewise I couldn’t grip the nice taper end in the 4 jaw chuck. So I decided to produce a brass bush that would protect the shaft with the taper [photo] leaving the larger diameter faced end to be held with the live centre.

Once the bush was drilled and reamed, it was parted off and the bush and shaft placed in the 4 Jaw chuck, using the dti again to get it running true. I decided (with fingers crossed) that I better check the shaft was true across its length and I was really pleased to find no discernable difference between ends. Now the test would be if my new chart with the dimensions on (chart is too posh a term for the scrap of paper – see photo) would work.

Starting with the end nearest the chuck, the digital readouts proved there worth as I set the position of the saddle into the correct position. With a new insert in the parting off tool I took the cut to depth. Set the y axis reading to zero and moved the saddle to the end position and cutting to 0.005” of the finished size. This left a middle piece to be removed, again to within the 0.005” of finished size. I now carefully moved the saddle between the two cam edges using the parting tool to turn down the last 5 thou to finish across the gap.

Then the saddle was moved towards the tailstock and into position for the next cut to within 0.005” before cutting the end position, removing the centre part last. This was repeated until all 8 cam blanks were cut. The tool was changed and the end nearest the tailstock then turned to finished size using the half method. Since learning about the half method I can nearly always get to the 1 thousandths of an inch allowance I give myself. Well unless I go stupid as I did earlier on in the day, but that wasn’t a failure of the methodology, rather the stupidity of the operator!!

And that was enough for me today. At least I made progress. Hopefully tomorrow I will be able to produce another blank (I would like to get both done really but that depends more on health issues than time ……)

At last I felt well enough today to get back out into the workshop. Nothing feels better than a successful or even semi successful session. It even gets better in that I was working on the Seal engine for the first time since the start of the Myford refurbishment.

It took quite a while to sort out the turning fixture for the camshaft with no parts fouling each other. I had to reduce the diameter of the front disc that registers the degree of rotation of the camshaft. Then there was a problem of getting the cutting tool to have sufficient travel without fouling anything. This all took time but eventually everything went around without anything going bang!

The cam blank I am using now was not made to match the fixture (my mistake) so I am going to complete the machining as a practice and confirmation piece. Confirmation that the process I am using will produce the correct camshaft.

To help me avoid mistakes (since I am cutting 6 cams at a time) I decided to mark which cam was which, on the offset turning fixture. This, together with the cutting charts produced for me by Steve Huck’s meant I had a chance of cutting the right cams in the right order. As an added safety measure I also marked all of the cams with a permanent marker. If those cams which had to be left remained covered with permanent marker ink, I wouldn’t have a problem!

For those of you who have read Steve’s cam article in both Model Engineering in the UK and Model Engine Builder in the USA (and available as a download on www,mikes-models.com), you will realise that ‘the first cut is the deepest’, as the song goes. Initially I need to remove 0.078” from all the Cam blanks, but in order. After that it’s a case of revolving the camshaft by 5° and making the cuts on the chart. I had printed out a set of charts already and filled the x boxes with a highlight colour then laminating them. However I decided to print a new set off and use a highlight pen to colour in the section that was being cut so I could keep count.

I need this amount of organisation since there are 47 rotations with cuts for the exhaust and 49 rotations and cuts for the inlet cams. So as you can see there is a lot of work to be done. Now multiply that by the 3 cams I will be making (this practice then two engines) and you will see this is not going to be quick!

More importantly though is the fact that I’m back!

Today’s session started later than usual and was more of a potter around cleaning up after the last few days work. I then spent time sorting out the filing cabinet fitted in the new frame between the Myford Lathe and the Milling machine. Quite a relaxing session really and perhaps that’s why about 1200 hours I felt up to sorting out the remaining two items for the camshaft turning fixture, for the Seal engine build.

It was really nice to get back to the lathe after all the ‘non’ critical work to build the new stand. After chucking the smallest diameter brass bar nearest to the finished size of the bush, it was simple enough to get to the finished size. I decided to hold the centre drill and finish drill in the ER25 collet system to be as accurate as possible and the hole drilled to form the bush.

About this time Mike (the MGA owner) phoned to check I was still up and said could he nip around to see the brackets. 10 minutes later he arrived and after bending the second bracket to shape (I wanted Mike to be there to confirm the layout). Because of the annealing process the bend went far easier than I anticipated being relatively soft for stainless steel. The bend was a little too sharp for my liking but Mike decided to take them home and check all was well. A visit over the weekend should see the project finished when Mike brings his lovely MGA to us.

That really seemed to form a natural end to the days work. So I decided to stop and spend the rest of the afternoon re reading Steve Huck’s article on camshafts  ready for starting the camshaft cutting tomorrow. Exciting times……

Edgar T Westbury’s Seal 15cc 4 cylinder petrol engine – update 3^rd March 2009

After several weeks getting the Myford ML7 lathe refurbished I have been desperate to get back to the Seal engine build. Taking my own advice for a change, I wanted to get one of the worst (in mind at least) aspects of the build out of the way early on, that of the camshaft. I have made the fixture to turn the cams on the lathe to a design by Steve Huck’s but now comes the metal turning itself!

Looking at the plans as supplied I cannot get my head around the dimensions given regarding making the camshaft blank. Feeling a little under the weather I thought that the best way forward would be to make up a machining aide memoir (similar to the approach I used when designing and making the Chess set featured in Model Engineer, issues 4345,4346 and 4347 : 2009) and try and make sense of the drawing. Eventually I thought I was there and would check my dimensions against a broken camshaft given to me by the seller of the casting’s set.

I intend to make two camshafts initially. The first will be made from stainless steel and used to see if I can get away without hardening the shaft as recommended by one or two HMEM forum members. The second would be made from steel which I would subject to the powder hardening process. I fully intend to make other camshafts for this engine later on when trying to improve performance. I hope to learn a lot more about small/miniature cams and their performance over the coming years. Don’t ask me why but the subject does ‘rock my boat’ as they say.

Anyway I chucked a length of ½” diameter stainless steel which measures 0.499” and since I am working to a tolerance of +/- 0.001” I will not take a surface cut. Because of the tolerance limit I have set myself I thought I would take time to check that the Turner lathe I have has the tailstock in line with the chuck. You may ask why I haven’t done this before and the simple answer is lack of experience. I also believed (wrongly) that the accuracy would be as good as it got when leaving the factory so leave well alone, in case I mucked it up. Its only the rebuilding of the Myford lathe that has given me the confidence and perhaps techniques, to check something I should have done as soon as the lathe was received.

I have always suspected something could be out of line from some long cuts done earlier. When using 2 DTI’s to check alignment I couldn’t believe it was over 4 degrees out over about 7 inches! The remedy was simplicity itself, with the tailstock moved to the correct position by using the adjusters, before being locked off. I decided to run the lathe up and run the saddle up and down a couple of times and recheck, finding everything now running true. I kicked myself for not doing this earlier. If I am fortunate enough to ever buy a new milling machine I will carry out checks on everything before even switching it on! Fear of the unknown has a lot to answer for!

With the confidence that the set up of the bar was running true in the 4 jaw chuck and in line with the revolving centre in the tailstock, I set too turning down one end to the 0.250” diameter required. Steve Huck when designing the camshaft turning fixture, recommended that I should leave extra at each end of the camshaft to be removed at the end of the cam profiling. So I allowed enough to clear the centre with the turning tool and then using the DRO moved to what I thought would be the correct position to cut the gap between cams. All was going fine, if slowly until it came to cut (or in this case leave) the second inset leaving the cam blank alone. Checking before I made any cut something did not seem right. I checked the measurement and compared them the broken camshaft and whilst the width of the cam was correct, the gap between them was not.

No matter how hard I tried I kept tying myself up in knots. I got so confused that I gave up and decided to call it a day. It was only when laying down this afternoon that by using graph paper to scale, that I could work out what the dimensions should be. Blonde moment over I have made a new sheet so when I fell well enough to have another go, I should at least know where I have to cut. I don’t say I will get it right, but I know now what needs doing but I thought the same this morning so don’t get too excited! To be contd.