Just had  a short session this morning and continued with the flywheel project for the Seal engines being built. However after getting the outside turning round and facing off I was left with 2.6315" diameter (need 2.5" finished size) so was pleased with progress. I don't know what specification the brass is made to but it machines great!

So feeling smug I thought I would rough turn the inside of the cavity (will be the rear of the finished flywheel) and using one of my home made boring bars before reversing the blank and bringing the front to roughly the correct diameter so that finishing cuts could be made all the better when running the lathe at faster speeds than the unbalanced blank would allow. This is when I hit a snag! One that I did not expect or had come across before using the Turner lathe.

The diameter of the cavity when finished, will be 1.75" and when I reversed the jaws, they were too big to go inside the cavity! So my smart thoughts went out the window! I will now have to remove the remaining excess by another method.

I did however resolve a question I had about the small diameter of the valve liners for the Seal. The answer came to me when studying the drawings last night and the reason is the need for the valve spring to sit over the outside of the valve guide. Mystery solved and I will just have to be careful when making them!

When I resume work on the flywheel I will hold the turned part in the 4 jaws as normal. A few photo's below show progress........

On one visit to my local scrap yard I was fortunate enough pick up a large diameter piece of scrapped brass. It had one problem, which I guess is why it was put into some factories scrap skip, a large cut on part of the bar, but fortunately it had enough unaffected to match the 2 ½” diameters needed for the flywheels.

Brass from my local scrap yard

The first task was to decide a machining procedure for the flywheels and after a little thought I decided that I would make a centre mark and scribe a 2 ½” diameter circle in the available space on the brass bar. This mark would be used to centre the brass  in the 4 jaw chuck by using a centre drill in the tailstock, using the pressure from the tail stock to hold the brass in position on the 4 jaw chuck.

Using the tailstock to centre the brass blank in the 4 jaw chuck

I will then face off the blank and turn the outside to a round shape before centre boring the cavity which forms the rear of the flywheel. Once this is done the blank will be removed and then use the 4 jaw chuck to hold onto the inside of the cavity, the front part of the flywheel will be turned and finished to shape. The final diameter however will not be completed until the flywheel is held on a mandrel running between centres as per Westbury’s suggestions, to get the flywheel turned accurate enough to eliminate wobble when used on the engine for real. Well that was/is the plan.

To save me some effort without producing mountains of swarf, I used the new bandsaw to cut away as much as was safe from the scrapped lump.  This blank was then taken to the 4 jaw and I decided it would be safer to reverse the jaws when holding the rough blank. They would be reversed again when the cavity is produced.

The blank was set up as per my machining plan and the first cuts made to the outside and this is where I decided that enough was enough. The next session will see the continuation of the turning of the outside until round before facing and then boring out the rear cavity of the flywheel. Look back and see the progress

Progress so far on turning the first of two flywheels for the Seal engine

Well today I managed to get back out to the workshop for a couple of hours. Since the cylinder liners have now been made it was time to start on the other cylinder fittings, namely the 16 valve liners (yes I am building 2 engines).

Having looked at the plans several times and referred to Edgar T Westbury's article published in Model Engineer (April 1947!) it seemed to me that since the guide must have the valve bore exactly central and to size, it would be better to use the 4 jaw chuck to make them.

I then considered the machining process to make the valve guides and due to their shape  the best way forward would be to produce phosphor bronze blanks. These would then be inserted into a special collet (yet to be made) which would allow me to produce all the blanks in one go (see photo of the first trial blank).

The blanks could then be inserted into the collet, which would be set to run true in the 4 jaw chuck. Then the very small 3/32^nd” central hole can be drilled and reamed before finally boring the ¼” diameter inset which needs a special HSS tool ground to shape, allowing the bottom radius to be turned.

Whether this is the best way to make the valve guides I am not sure, and if you know a better way then let me know before I start the job in earnest. Edgar’s article is very skimpy on making the valve guides and this worries me in case there is an easier way to proceed.......A second question arises in my mind in relation to Edgar’s design. Again I will have to do further research since I cannot see why he would have produced the guide with such a small diameter bottom end. It is only 5/32” in diameter and the valve stem is 3/32” in diameter. Making it larger would have the benefit of allowing a larger diameter valve stem, although that may have an influence on the inlet and exhaust volumes......

I may have missed a very good reason for his design being so, so I decided to put further work to one side on the valve guides until I know more and push ahead instead with the 2 flywheels.

Valve guide on the Block casting

]]> http://myfordengineeringauction.com/model-boats/seal-engine/seal-15cc-4-cylinder-valve-guides-and-flywheel-under-way/feed/ 0 http://myfordengineeringauction.com/model-boats/seal-engine/seal-cylinder-liners-completed-%e2%80%93-need-honing-and-fitting-now/ http://myfordengineeringauction.com/model-boats/seal-engine/seal-cylinder-liners-completed-%e2%80%93-need-honing-and-fitting-now/#comments Tue, 19 Jan 2010 22:37:24 +0000 Steve http://myfordengineeringauction.com/model-boats/seal-engine/seal-cylinder-liners-completed-%e2%80%93-need-honing-and-fitting-now/

Pair of Edgar T Westbury's Seal 4 cylinder 15cc engines

Today saw another visit to the workshop and I continued with the task of making the 8 cast iron cylinder liners needed for the pair of Edgar T Westbury's 15cc 4 cylinder petrol engines I am building. Now real problems were encountered and the finished sizes all came within the 1 thou (0.001") tolerance I set myself. The methodology of halving the last few cuts really does make a difference i.e. if there is 0.012" left then the next cut is 0.006, followed by 0.003 etc. Since following this rule and with the digital readouts help I can hit finish sizes  required.

The photo's below show the cylinder liners made. On one I have forgotten to make the chamfer at the bottom of the cylinder so will need to make a collet to hold the liner when I re chuck the liner to cut the chamfer. Steady, if not dramatic progress.

The reason for buying a replacement bandsaw was to increase the capabilities for metal cutting in my home workshop. My 'old' Warco bandsaw was bought 3 or 4 years ago and to a budget. However, with increasing experience comes greater knowledge. My local source of metal is a scrap yard which means I have all sorts of sizes of cast off's from local industries.

One prime example is a 'lump' of brass that has a part saw cut through the better part of one side. Now I have the new Clarke Bandsaw I can at last cut off sections of the brass lump which I will use to make the two flywheels needed for the Seal 15cc 4 cylinder, petrol engines I am making at the moment.

Once this job has been completed I will put the bandsaw into its vertical position, attach the table and attempt to cut the special steel bar bought for the crankshafts. It is tough steel so I have bought a bi-metal bandsaw blade (has HSS teeth) and see how it performs. A job that the old bandsaw could not tackle (not that this one has yet!). Time will tell.

I decided to upgrade my bandsaw to a larger model and importantly, one with the ability to work upright. The best model for price I could find was the Clarke CBS45MD (4½" X 6") Metal Cutting Bandsaw from Machine Mart UK.

It has a cutting capacity of 105mm (4") round, 100 x 150mm (4" x 6") flat at 90° and a 500W, 230v / 1ph motor with combined ON/OFF & safety No-Volt-Release switch.
The bandsaw has 3 cutting speeds (5/95/165 feet per minute)with spring tension arm control & adjustable vice for cutting angles 90 degrees - 45 degrees and twin wheels for workshop mobility.

I placed the order just before the UK VAT tax went up and the bandsaw delivered a couple of days ago. I must admit to some surprise at the amount of work let to the purchaser. This included attaching wires for the safety cut out on the pulley cover.

My main thoughts so far is that its a lot of metal for the money. However there are a few 'niggles', the most important of which is its stand and the manoeuvrability of the saw, both of which are poor. The metal for the stand is far to thin and does not help with moving the bandsaw around. The weight distribution and low position of the handle make it very difficult to move. My previous smaller bandsaw was stored (still is...)on a home made stand with castor wheels and the working height set to suit my own requirements.

On opening the box the many parts were checked and a 'fittings' bag ticked off. However the number of bolts in it did not match the assembly needs. Not so much of a problem as I am well stocked with fittings of my own, but still not as it should be.

The next trial was in working out a system to place the 60+ kg weight of bandsaw on the flimsy stand. Considering I am disabled this took some sorting out with packing a part lifts. In the end I gave up on that approach and since the saw decided to relocate itself onto the floor sideways on, I managed to bolt the frame on. However there was no way it could be lifted until another pair of hands arrived.

When trying to move the bandsaw on its own system of two rear wheels and a simple handle the bandsaw was difficult for me to move around. Something that is very important since I store the bandsaw away and have to move it each time its needed. So a better solution was needed and I set out to find some castors locally. On return some angle iron was found to make the wheel brackets from and of course it needed cutting.....this is the point where I began to see past the problems and saw the capabilities of the saw for the first time.

After making the brackets and fitting them the wheels proved too small for the anti fatigue rubber flooring in the work shop. So I am now waiting for some 75mm castors to arrive. However, there may well be another problem with stability, even with larger castors, as a trial cut on the small ones showed it could wobble..........

I then decided that I would try the saw out in its vertical position and I was becoming more impressed with its performance, if not the quality of the flimsy stand.

So I have a new and capable saw but need to sort out its storage and manoeuvrability before I can jump for joy as it were. Still if the worse comes to pass I can 'adjust' the previous band saws stand by making it longer, just more work than it should be. The stand is very much its weak link.

Seal Cylinder Liners - Session 1 09-01-2009

Well a start has been made at last on the pair of Seal Engines I started this time last year! There are 8 cylinder liners to be made and they are turned from cast iron. I was soon reminded on how dirty cast iron is to work. Fortunately I remembered enough to protect the lathe as much as possible from the swarf.

The first cylinder is 3 thou oversize so its piston will have to match, that is of course unless I remake it in the end. My excuse for the oversize is the new honing methodology I am trying. It comes expensively from industry but its performance is exceptional and quick!!!!

The allowance I made of 2 thou undersize first time before honing proved to be insufficient! The second one came in 1 thou over when honed which was within the tolerance I set myself. Now the lesson has been learnt the others should come out the same, but I suspect I will need to make more than the 8 (already one down out of two!!!).

Edgar T Westbury, the engines designer, recommends painting the cylinder liner with paint or varnish when pressing home and for the liner NOT to be a tight fit. I will wait until later before making up my mind what, if any, sealant I shall use.

Unfortunately no work has been done on the furnace or any other workshop items in the last few weeks, but hopefully after Christmas I will be able to resume work on all my projects. In the meantime  here are a few photo's of the work  already completed when making the crucible tools.

First priorities when resuming my workshop time will be completition of the furnace. I will need to make another top though because the first was not successful. That said, comparatively little remains to be done before it can be 'fired' up. Look out in the new year for some 'flaming' pictures.

Mike