Member postings for Gas_mantle.

Hi,

Other commitments meant I didn't get a lot done today however I did manage to finish the cylinder head and get it fitted.

After a while thinking about it I decided to stick with the 6 hole version that I've already made and hope I have enough room in the cylinder walls to drill and tap. There's only really one hole near the base mounting face that is risky but I think with care it's achievable so here's how it went

Firstly I gave the cylinder side of the head a tidy up, I'd cut this face off in the lathe by parting it off so it needed a bit of filing and emery paper to clean it up a bit

Next came the bit I wasn't looking forward to - drilling the cylinder block. Since the head mounting holes are slightly out of line I used it as a template for locating my drill, although I forgot to take a photo.

Anyway you get the idea and can now see that it's only the hole against the base mounting face that is likely to cause problems. I did cheat a bit by putting 2 thin shims under one side of my drill vice to try and coax the drill bit to cut very slightly inward.

Similarly with the tap I've tried to gently persuade it inward - so far so good.

Maybe not precision engineering at it's finest but I did get away with it - just.

All holes tapped and head bolted on.

With hindsight I think I was pushing my luck a bit trying to get 6 bolts in rather than 4, if I was to make another of these engines I'd be inclined to stick to 4 holes next time.

Having said that, it did turn out ok and although one of the holes is a tad out of line I'm pleased with the result.

In doing the head this way I've now committed myself to doing the other end of the cylinder the same way but next time might make the radius of the bolt ring a tiny bit smaller without it being visually noticeable.

Peter.

Hi,

The reason the flange is a bit thicker is actually a mistake - I misread the plan and included the width of the raised part in the overall thickness. I did think of making another one but I'm happy enough the way it is and the seems to be ample room to make the piston end cover the same thickness. I do like the look of it but I did drill one hole a tad out of line

Jonathan - I'll ask the member who gave me the plans if he'll forward you set.

Peter.

Hi,

I had intended to start on the valve chest today but after reading earlier advice I've decided to put it off for a few days till I've had a think about it The cylinder head looks fairly straightforward so I chose to do that instead.

Firstly though I wanted to cut the steam passages into the end of the almost finished cylinder. It's a simple matter of cutting a 2mm deep slot linking the steam inlet to the cylinder at either end.

Without access to a mill I decided to use a small Dremell type hobby tool. It's not pretty but should do the job

Now for the cylinder head, basically it just involves machining a 5mm thick disc with a slight raised centre on one side to locate in the cylinder and drilling holes for securing bolts.

Firstly I turned the the stock to size and used the tool to scribe a light 12mm radius witness mark to position the bolt ring later.

As I machined slightly more off the cylinder walls than the plan required I thought it best to have a quick check that 12mm radius for the bolt ring looks ok.

Sure enough a ring 24mm in diameter looks to be fine.

Although not on the plans I thought a slight recess on the outside face would enhance the appearance a bit. I also wanted to see if I could fit a ring of 6 bolts in rather than the 4 on the plan.

What seemed like a simple idea proved to be more awkward than I expected, I'd overlooked the fact that the tool I was using had insufficient clearance and it wouldn't allow me to get a square corner in the recess.

I thought a parting tool might just about manage as I only want to remove about 1mm of aluminium but even raising it a shade above centre it wouldn't clear either.

Hopefully this will do the trick.

At last !

The other face requires a raised portion 1.5mm deep to fit flush into the cylinder.

If I can get away with it I'd like to secure the head with 6 bolts rather than the suggested 4 so marked the end and scribed a very rough free hand approximation of where the bolts will lie. Although a very crude method I'm satisfied I can get away with 6 holes.

Having drilled all the holes I do like the appearance and think the recessed centre adds to the look but I did get 1 or 2 holes slightly off centre.

And how it would look with hex head bolts.

I'll have a think about it overnight before drilling the cylinder.

Peter.

Hi Jim,

Thanks for the help, I'd be interested to hear any other comments / suggestions etc as I go along.

I'm sorry to hear you broke the tap, I've just bought myself a set of 2.5mm ones as previously the smallest I had was 3mm but this engine has quite a few 2.5s. I haven't used the taps on anything yet so I'm hoping they'll work ok, depending how today goes I may be using them later.

Peter.

Hi,

Thanks for the feedback

Stew - I had planned on drilling the steam chest today but after reading what you've said I think I'll hold off for a day or 2 till I can get some plasticine or something similar.

I think what I'll do is one of the cylinder end covers and cut the 2 passages into the main cylinder bore.

Thanks

Peter.

Hi,

I managed to get a bit further yesterday by facing off the second face off the cylinder block and drilling the steam ports as well as drilling the base mounting block.

The procedure was the same as the first face but with the added constraint of ensuring it was at 90* to the first one, I wasn't sure how best to go about this but came up with this rather makeshift idea. The first machined face can be seen upwards in the chuck, what looks like a set square is actually a packing piece at the front and one of my parallels firmly pressed against the machined face - by reading the height of the parallel over its length I was able hopefully get the second face at 90* to the first.

Success - it worked.

Next job was the simple task of drilling 2 holes 30mm apart in the mounting block, I decided to do the block before the cylinder as I might use it as a template to correctly position the corresponding holes in the cylinder.

I've only had this drill a fortnight and this is the first 'proper' job I've used it for so I thought a few basic checks on it's alignment etc wouldn't go amiss.

A simple job but now I have a decent drill and a vice it's so much easier.

The next task is a tad more tricky - it involves drilling in from either end to a depth of 18mm then drilling 2 shallow holes in the face to (hopefully) meet up. I've marked out and punched the centres, using a better set of punches has greatly improved my accuracy compared to the blunt pencil of a punch I was using previously.

Well here we go - the plan suggests 3mm holes but as I machined slightly more off the flat faces to fit my bar stock than the plan, the cylinder walls are a little bit thinner so I decided to try at 2.6mm first then reassess the situation.

Now a shallow 4mm inlet hole and lets hope they meet.

Well the first one meets perfectly, let's hope the second one goes to plan also.

Second one also proved to be a winner and I'm pleased with the result so far.

Next job tomorrow is to cut a small passage at either end leading from the steam holes into the main cylinder bore.

It can be seen in the photo how thin the cylinder walls are after going through with a 2.6mm drill - I think it's too risky to open them out to 3mm - anyone else got any thoughts ? I'd like to run this engine on live steam occasionally, is a 2.6mm steam passage going to significantly restrict the flow of steam on an engine this size compared to a 3mm hole ?

Cheers

Peter.

I don't know how others go about it but I make a mandrel as a 'one use only' item, once you remove it from the chuck you'll find it very difficult to get it back on centre for multiple uses.

I'm not saying an expert can't do it but as a beginner I'd far sooner spent 10 mins making a new mandrel knowing it will central to the lathe axis.

Brian,

I don't know how big you are intending to make wheels but here's a mandrel I made for a wheel 20mm thick wheel (I think 65mm dia) it worked fine and I'm sure using the same principle I could make one a bit bigger within reason.

Hi all,

Well, my drill vice and grinder have now arrived along with a decent set of punches as suggested earlier so I'm hopefully in a position now to continue with this little engine.

I decided I'd have a go at making the cylinder block. This basically consists of an aluminium rod turned and faced to size and accommodating a 16mm bore along with the steam ports and fixing holes located on 2 flat faces 90* apart.

First things first, I turned the aluminium to it's final 32mm OD and faced off one end. Although a simple operation I was well pleased as the tool I used (visible in the pic) was the first home made one I've used on my new grinder and after only a few minutes making it was pleased to see it does a pretty good job for a first effort..

The bore needs to be 16mm so I need to drill it out up to my maximum drill size (13mm) and bore out the remainder.

I did have a go at making a boring bar of my own but it turned out to be a bit too big for this task so rather than maker a smaller one I decided to try the 8mm shank carbide tipped one I already have. This tool probably hasn't got the necessary reach for the depth I need but I found a brazed tipped bar I forgot I had. All I needed was for the first bar to open out the bore large enough for the 2nd (larger) bar to do the final finishing.

The maker states the tipped bar will fit a 10.5 mm hole - I've no doubt there claim is true but it would take someone far more skilled than me to do it. This photo is against the 13mm hole and there isn't a great deal of clearance.

This is the bar I forgot I had - it came free with my machine as part of a set of 5 tools, I couldn't get on the with the other tools so never really used this. But needs must, my 8mm bar isn't up to the job but has at least opened up the bore large enough to give this a try.

Pleasantly surprised I found it did a decent job.

Just need to part off now.

The cylinder will ultimately sit on a base of aluminium square stock so I now need to machine a flat face parallel to the bore. I don't have a mill (this engine is specifically designed for people without access to a mill) so I'll cut the face by facing off crosswise in the lathe chuck.

The valve chest will be made from a similar piece of aluminium square so I actually need to machine 2 faces at 90* to each other.

Making a guest appearance is my homemade tool post dial indicator support. I figured that for smooth running having the machined faces parallel to the bore was important so spent quite some time getting this as accurate as I could.

So far so good, the first cut seems to suggest it's parallel. The finish isn't great in this image but closer to my target dimension I took smaller cuts at higher speed to greatly improve things.

Hardly rocket science I know, but I'm reasonably pleased with it so far.

Next job, machine the other flat face, I haven't decided yet whether to drill the fixture mounting holes now or after I've machined the parts they are to secure.

Thanks

Peter.

Edited By Peter Nichols on 05/09/2015 11:25:02

What looks like a chip I think is actually the edge of the topslide showing from behind, if you look it's line with the rest of the slide to the bottom right of the tool.

I'm no expert but surely you are making a lot of work for yourself here.

Why not just turn the end of a piece of stock to a diameter that is a very close fit to your flywheel axle hole, cut an external thread on the end then use a nut to secure your wheel. I've done it a few times now and never had any problem using it for small wheels.

Make sure the mandrel shoulder is at least a wide as your wheel hub so that you have a solid true running face to press up against. So long as you don't remove the mandrel from the chuck till the wheel is finished and it's a good close fit you should be able to turn the wheel over to machine the other side.

Hi Jason,

Thanks for that, I can see what you mean and will have another go at it tomorrow.

I did a Google search but although I found a lot about general tool grinding I couldn't find out much concerning boring bar angles.

I'm hoping to try and have a go making the cylinder for the Potty mill engine tomorrow.

Peter.

Hi all,

Thanks for the advice.

My grinder arrived today so I've managed to knock up a primitive looking boring bar using an old drill bit and some steel rod.

I've never done this before so wasn't sure about the angles etc. I'll see how it works tomorrow at least now I have a grinder I'm in a position to experiment till I can get something that works.

Peter.

Edited By Peter Nichols on 03/09/2015 17:51:38

Looks very much like a right hand knife tool to me :-

**LINK**

Hi Brian,

My guess is because of different terminology people are getting confused as to what centre you have and what you are trying to do with it.

If you can elaborate a bit more I'm sure more people will help.

Peter.

Edited By Peter Nichols on 02/09/2015 11:57:52

Nice work Nick, I'll look forward to following this thread

Peter.

Hi David,

Thanks for your help, the Muncaster site has some interesting plans, I'd never heard of them before but will take a proper look at their info later.

If I thought I could build one I would, but at the moment realistically it's beyond my skill level

Peter.

Hi,

I've just ordered a grinder yesterday, I already have some HSS blanks that I want to experiment with making 'ordinary' cutting tools but I intend to have a bash at making a boring bar as well.

I have some more materials on order for the 'Potty' mill engine I'm building so I really want to get properly started on that and need the tooling necessary to bore the cylinder.

Peter.

Hi all,

I stumbled across this short video of a rather attractive little wobbler a few days ago and was wondering if anyone knew anything out this type of engine ?

**LINK**

Is it a copy of a full size engine somewhere ? has anyone on here built one similar ? Are there plans for it ?

It seems to have an attractive finish to it that makes it look old but is that artificially added and the actual engine is relatively modern ?

I'm sure you'll agree that although it hasn't got all the complexities of eccentrics, rods, valve gear etc it is nevertheless an attractive engine and makes a great sound when running slow

I have messaged the guy who posted the video in the hope he'll tell me more but so far haven't received a reply.

Peter.

Surely the leadscrew bearing at the tailstock end will prevent the carriage moving that far ?

I was able to adjust the carriage lock bolt on my machine from underneath, it's a bit fiddly but shouldn't take more than a few minutes.

As for the Allen bolt idea of locking the carriage on these bench lathes it seems to me there must be a better way, invariably the compound slide is over the bolt head and makes getting the key in a bit of a pain. I thought about grinding down the short side of an Allen key and leaving it in situ.

Peter.