Poppin Engine build.

[ian_in_the_midlands]

Following people kind enough to answer my questions, and requesting I do a log of the build, here it is.

Be aware - this is not a "how to". I have no idea what I am doing as I have only owned a lathe for a couple of months, and the only engine I have built so far is the simple Elmer's wobbler.
I am using the poppin as a project to learn about machining, so any constructive comments will be welcomed.

First the pictures of where I am now.
The cylinder and cylinder head are finished, and the piston has been made.

My first attempt at lapping the cylinder by hand ended in disaster with the centre becoming a larger diameter that the two ends.
I used an adjustable reamer, taking very light cuts to get back to a cylinder. I then turned the piston to be a tight fit, and brought it down to size using very fine abrasive. It is now a lose but airtight fit. In the picture the cylinder looks quite rough, but I think this is an optical illusion. I will wait to see if the engine runs before trying any lapping again.

[ian_in_the_midlands]

This afternoon I started on the crank.
The plan calls for 7/32" x 1/4" steel.
I had some 1/4" key steel, so this was faced down in the lathe to the size required.
This was then sawn in half, and marked out.
The holes were then drilled in the lathe with the two parts held together in the chuck. The holes will be reamed to final size when my reamer arrives next week.

I plan to silver solder the crank parts together - something else I have never done before.

[dawesy]

Looking good. Must have a ho at something like this.
Keep up the good work ;)

[Stilldrillin]

Hi Ian.
Watching.... Reasonably quietly. 

How did you lap the cylinder? I often find mine are slightly small, in the middle...... 

David D

[ian_in_the_midlands]

For the attempt at lapping that failed I made an aluminium lap, and using fine grinding paste, held the lap in the drill at slow speed, and held the cylinder in my hand, trying to feel for tight spots.
I had read there is a danger of opening out the ends too much. That is probably why I concentrated too much in the middle.

After correcting the problem with an adjustable reamer, the piston feels a constant fit all the way through.

[dawesy]

Myfordboy on you tube did a video on lapping a cylinder.
If this one needs it (though it sounds like you've got it spot on) it could help.

[Stilldrillin]

This is my method.

Piece of dowel. Minus a thou or so, on bore size.......




Smear of fine grinding paste. Plus oil, as time goes on. Around 80rpm.......




The cylinder is oscillated backwards n forwards. Reversing occasionally on the lap. Until all feels smooth with no tight spots.

Works for me! 

David D

[ian_in_the_midlands]

I have seen the video from myforboy where he is lapping a cylinder. One of the few videoes I could find showing the lapping actually being done. I have watched and enjoyed alot of his videos. If I find I do need to lap the cylinder I will try your method David. Thanks. Before I do that though I may polish the cylinder a little using the piston. What abrasive,  if any would I use for this? I do not want to risk anything that might embed itself into the cast iron. Someone recommended tooth paste but that seems a little course.  I thought maybe just using oil or possibly powdered chalk?

[lordedmond]

Fine grade Time Saver powder is the bees knees for laping

It breaks down during use and becomes none abrasive , it can and is used in industry to bed in gear boxes the fact that it breakes down meand that the gear box will not need dismantling for cleaning

I will get a link

Here you go

http://www.steamsupplies.co.uk/category/engineering-supplies/sub,36/30/1/0

Stuart

[gmac]

And a booklet to go with it.....

http://www.newmantools.com/lapping/timesaver_booklet.pdf

You made me go looking.....

Cheers Garry

[ian_in_the_midlands]

A bit more progress today. The second pair of holes were drilled and reamed on the crank. I couldn't align the bars together in the lathe so had to use the drill press. Took ages to get everything right, but everything looks parallel and square. Back on the lathe to radius the ends and turn to length. I was careful to use very light cuts for this one.
Finally a quick rub on a coarse diamond stone to remove the chuck marks, and parts are put together while I decide how I am going to fix them.

[ian_in_the_midlands]

I now need to decide if I am going to threadlock and pin or silver solder the crank together.

If I go with threadlock and pins, is the grade of theadlock important, or will any do?

As I have not silver soldered before, I thought it prudent to do a practice bit first.

3 holes drilled and reamed in some key steel.
1 left like that, 1 chamfered, and the third chamfered with some grooves filed to help the solder to wick up.

I will see what I can do tomorrow

[Stilldrillin]

Ian.
I prefer Loctite 270, (any will do, I guess), plus 1mm dia cross pin.

Have a look here. About half way down the page....... http://madmodder.net/index.php/topic,8821.0.html

The m2 grub screw, locating into a dimple. Allows dismantling, and accurate re-assembly.

Still going strong! 

David D

[dawesy]

Coming along nicely

[ian_in_the_midlands]

My first attempt at silver soldering was not good.
I has trouble getting the solder to melt and flow.
I had carefully cleaned and degreased so suspect I had not used enough flux.
3 pictures below are the results after a rub on the diamond stone, the results after a savage attack with a hammer, and a shot from behind showing the solder had wicked through the filed slots.

Although the first two pins did fail eventually, they took some abuse before they gave. I can see little or no evidence of solder, but surely the oxide can not hold that hard?

The third joint held firm, but does not look very good as the solder had not flowed around the chamfer.

Loctite 2700 and 1mm steel for pins have been ordered.

[lordedmond]

Not hot enough
Or burner not big enough, you really do need propane butain is ok for small jobs

For the low melt SS you need a good 650 deg C or a dull red but it must be all up to temp.

Remember the SS will flow towards the heat , therefor you controll the flow

As a final point flux I use T5 it stays active longer in the heat and is more aggressive as a result when the joint is hot enough the flux will go clear and the joint will look clean, yes it's a bit harder to clean up but a soak in citric acid sorts it out

Stuart

[ian_in_the_midlands]

A bit more time in the garage this afternoon, making the cam washer and two flywheel hubs. I will have to wait for the die to arrive before I thread them. A good chance to try out my new collet chuck. Don't know how I managed without one before.

[ian_in_the_midlands]

More work on the crank.
Assembled with green threadlock yesterday. That stuff doesn't give you much of a handling time does it!
My plan today was to drill through and threadlock in some 1mm pins.

Confident this would be okay after doing a test piece, I managed to snap a drill off in third hole.

Managed to drill/bash the broken bit out, but it all looked a mess once I had finished.
A change of plan. The holes were opened out to 2mm and the both ends were countersunk by a small amount.
Panel pins were cut to length and peened to fill the holes.
The sides were then flattened off using a diamond stone.

Not perfect, but disaster avoided. A shame I am a poor shot with the hammer as I have left some small marks on the edges.

[lordedmond]

Ian
At the risk of telling you how to suck eggs , when you cross pin webs do not countersink or do any work on the hole edges that way when you press in the pin and dress it off it will not be seen .

Stuart

[ian_in_the_midlands]

That is the sort of advice I am on here for Stuart.
Too late for this one, but I will know next time. Thanks.

Centre now cut out and filed flush.
I think I have got away with it.

[ian_in_the_midlands]

Progress today: Hubs threaded, and two nuts made.
Picture added of parts assembled.

I also made a guide that will hopefully allow me to drill holes that match in the cylinder head and the standard.
My method of determining the placement of the 4 holes was to used a punch mounted in the tool holder, making a mark horizontal with the centre then and rotating the piece 90degrees. The correct rotation was determined using a square. This was repeated 3 times.

When the holes were drilled they aligned with holes already drilled in the top of the cylinder head, so my strange method must work.

Any suggestions for a better method I could have used?

[ian_in_the_midlands]

What bearings should I be using?
As the shafts are 4mm, I was looking for 4x8x4, but can't find any.
I could use the bearings in the picture?
They are slightly larger diameter at 4x9x4, but I can increase the size of the standard to cater for this.
Would these be good enough quality?
Would I have to remove the shields to lubricate them?
Will they work with the shields removed or would they simply collapse?

[Stilldrillin]

Ian.

I would use the 4x9x4, with the steel shield in place.

Occasional lubing with light oil, will penetrate. No problem!

This is what I use, for this kind of purpose..... http://www.ebay.co.uk/itm/50ml-Ballistol-Universal-Lubricating-Maintenance-Oil-for-Shooting-Fishing-DIY-/380659885378?pt=UK_SportingGoods_Hunting_ShootingSports_ET&hash=item58a118e542

David D

[ian_in_the_midlands]

I moved onto making the cam today. I started off with a mild steel bar of 28mm diameter.
The end was faced off, then I cut off 1.5mm. This was turned around in the chuck and an 8mm hole was drilled and reamed in the centre.
An 8mm mandrel was turned and my new "washer" was threadlocked onto it.
This allowed me to face to width and turn it to 1" diameter.

I then made a guide of 0.6" diameter into which I could screw the cam. Using a grinder/file/diamond stone, a flat was made that just met the guide.

I had no way of measuring angles directly, so I measured a chord of 20.81mm from the end of the first flat, and ground/filed/stoned a second flat up to that mark. This gave me the angle I needed (if my maths is correct).

The waste was then removed all the way around up to the guide. I then finished off with some emery paper.
I don't think the results look too bad.

[ian_in_the_midlands]

Today I made a start on the flywheels.
I turned some 2 1/2" brass down to 2 1/4" - leaving it 1/4" oversize. Two disks were cut off and faced to width.
The centre recesses were bored, but left a little under diameter. A centre hole was then drilled and reamed to 8mm in both wheels.

I made a mandrel out of aluminium. The plan is to keep the mandrel in the chuck to ensure concentricity, and use this to hold the flywheels, take them to the to final dimensions.
I used aluminium in the hope that it will mark the brass less than steel would, but I have some concerns that it may not be strong enough.
I will make up my mind if I use it or not tomorrow.

[ian_in_the_midlands]

Slow progress today.
The aluminium mandrel (should I be calling it an arbour?) was used.
Both flywheels were turned to final diameter and the centre was bored out.
I had problems with chatter. I suspect this was caused by flex in the soft aluminium, and maybe a blunt tool.
Then the centres for the 4 spoke holes were marked and centre drilled.
The tool marks were polished out before drilling out the holes.
I started on the pillar drill, but it was apparent that I was going to get a grab, so I fitted the 4 jaw chuck and started boring on the lathe.
Near disaster - I did get a grab, and the wheel was pulled from the chuck. Luckily the flywheel was not in too bad a shape. Some small marks around the circumference that I will be able to turn out without losing much of the diameter.
The wheel re-chucked, I bored again, this time going up in smaller increments. The first two holes went okay.
It is getting late now, so stopped whilst still ahead.

[Stilldrillin]

I like the way you made the cam, Ian! 

It's all shaping up, nicely........   

Any suggestions for a better method I could have used?

If it works for you, and the part is correct. That's the best method........ 

David D

[vtsteam]

I've been following Ian, and you've been doing very nice work while learning.

One question, did you stone a tiny flat on your drill tip lips before trying to drill the brass flywheels? Otherwise brass does really tend to grab.

Kind of hard to explain what I mean by "a flat" , but if you place the drill vertical tip down on a table, the direction of the flat would be parallel with the axis of the drill -- vertical. And it is very slight amount of stoning -- almost invisible.

I usually lay the stone flat on the bench, hook one lip of the drill bit over the edge on top, with the drill bit running parallel with the edge of the stone, and give it a swipe along the length of the stone. It should be a fine stone. Then do the other lip.

[ian_in_the_midlands]

No I haven't.
Somebody told me that that drills for brass are ground differently.
My previous attempts of grinding drills have been hopeless, so I thought instead I would just use brand new drills.

If it is simply grinding a flat I would hope I could do that.
I will investigate.

Thanks.

[Stilldrillin]

Have a look here, Ian.

http://users.bart.nl/users/summer/16mmngm/Articles_htms/ColinBinnie/DrillSharpening.htm

David D

[ian_in_the_midlands]

Back onto the flywheels today.

The set of drill bits I have are Tin coated, so I could not flat the end as advised. As most of my drilling is probably in brass, I will buy another set and modify them.

Too impatient and the in-laws over, I needed to get on in the garage, so I continued with the drills I have. Taking the holes out very carefully in 0.5mm increments, I had no more problems.

I then reamed the holes to final size, and finally gave each one a tiny chamfer with a drill bit.

The wheels were then re-mounted onto the mandrel, and the chuck marks were skimmed off. The wheels 'rang' as I was doing this, and the result of this can be seen on the finish of the rims. Varying the speed had no effect on the surface quality. The picture looks much worse than it is, and a polish with emery paper removed this marks. The wheels are now slightly smaller (0.5mm in diameter, 0.2mm in width) than the plans ask. I do not think this will make any difference, but that will teach me not to turn to final size too quickly.

It can be seen in the picture that there are still some chatter marks on the inside of the rim. I can not get rid of these so will have to live with them. I will put the worse side inward when I assemble the engine so that they are not so apparent.

Finally I mounted both wheels on a piece of steel, pushed the bearings on the end, and held these in the lathe. Spinning the wheels by hand showed a minute amount of wobble on one wheel. I will wait until the engine is assembled  to see how bad the problem really is before I start trying to fix anything.

[ian_in_the_midlands]

After looking at the pictures posted I had to go and check  - I think the marks on the first photograph that look like awful scratches on the spokes must be thumb prints, as I can not see anything there now. Panic over!

[ian_in_the_midlands]

This weekend I moved onto the connecting rod.
A length of 2.5mm silver steel was drilled and cut to length.
I decided to harden the piston end, so it was heated to cherry red and quenched in water.
I then re-heated it to straw colour and let it cool naturally.

Slots on the brass parts were cut using a slitting saw with the piece held in the tool holder. The sides were then milled to size.

Everything else was basic turning/ drilling/tapping.
Once assembled, the hole for the crank was drilled and everything was polished. I turned a wooden dowel and used brasso to get inside the hole.
The steel shaft was then threadlocked in place. The photo shows how I aligned the axis by eye. The plans call for a rivet to hold the shaft in place, but I will leave this for now in case I need to adjust the length in the future.

I made the yoke a few days ago, again using the slitting saw.

The parts were then assembled. There is a slight skew.  I suspect the hole may not be quite straight. I think it will be okay.

The yoke is attached by a piece of drill bit. It is only a press fit, but it is long enough that the inside of the piston will stop it falling out.

[ian_in_the_midlands]

Everything assembled. Starting to look like an engine.

Now to make a start on the standard.
A 2" length was sawn from a piece of 1"x2" aluminium flat and faced off in the lathe to size.

That's enough for today. Now time to work out how I can make the standard without a milling machine

[vtsteam]

You're doing a really beautiful job, Ian. 

[Manxmodder]

 Progressing nicely,you're doing a grand job Ian  ......OZ

[ian_in_the_midlands]

The weather has warmed up a little, so back in the garage to continue with the standard.
Holes were drilled/bored/reamed.
The drilling guide was used to drill the 4 holes through which the bolts will pass that hold the cylinder on.
I am unable to check alignment of these yet, but fingers crossed the holes are in the right place.
I also made the base.

I now have a problem: How to remove the material to complete the standard.
To keep things simple I will keep with square edges rather than the radiuses on the plan

My options are:
1. Drill/saw out the waste and file. Good practice with a file, but is this really practical? Am I more likely to end up wrecking my work?
2. Buy a milling machine. I can not find the room in the garage without selling my woodturning lathe. I need to think hard about this option in the future.
3. Buy a milling attachment for my mini lathe. So far the majority of advice seems to be to avoid this. I am still looking out for one at a sensible price.
4. Find someone with a milling machine willing to help me. I will try a post in the "Request for work" section.

In the meantime, there are of other parts for me to be getting on with.

[vtsteam]

I'd just file it -- it doesn't look like that much work. Rough the convex parts first with a nice big rough cross cut flat bastard file, then finish with a finer file. The hollow can be done with a coarse rat tail and a finer round file, the same way

You could cut out a profile of each end from thin sheet steel using tin snips and a file to smoothe it,  and attach it to both ends of the block. These will serve as guides, if you're worried about spoiling your work. File close with the rough file, and then file to the guides with the fine file.

Filing is fun.....if you treat it that way, and you aren't working for someone else! 

[ian_in_the_midlands]

It is not the amount of work in the filing that concerns me, but my level of skill. Anyway, with your bit of encouragement vtsteam, I thought I would have a go.
After marking out, the holes were drilled at the corners of the waste. The main lump to go was then removed with a drill/jewellers saw/hack saw as close to the line as I dared.
Some filing was done to get close to the lines, bit I need to order some smaller files before I can get into the gap and complete this.

I could now test the cylinder fit against the stand.
It was bolted in place. I am very slightly off to one side (very slightly isn't really an Engineering  term is it?). I must have bored the large hole slightly off. It is so small an error that this will probably not show once the standard has been polished.

The good news is the cylinder is upright  .

Thought I would put the flywheels on for effect  .

[NormanV]

In engineering there is precision and there is "what you can get away with". I am often surprised with how much I can get away with. Just keep trying.

[Stilldrillin]

Ian.
If you don't tell us. We'll never know about your, "good enoughs". 

You're doing a great job. Progressing well...... 

David D

[SwarfnStuff]

"(very slightly isn't really an Engineering  term is it?)" Oh I don't know? It fits right in there with, "a whisker, a smidgeon, (aka smidge) and a tiny bit".     Depends on the accuracy really needed for the job in hand.
John B,
 p.s. I guess i shall have to look at reply with quote.

[ian_in_the_midlands]

Weekend spend sawing/drilling/filing.
(Note to myself - find space in garage for milling machine and buy one!)

I decided I would follow the plans and put the radiuses in.
I still have some more filing and polishing to do. I also need to cut the slots for the crank and tap the holes for the screws that clamp the bearings.

Some pictures of the progress:

[Stilldrillin]

Weekend spend sawing/drilling/filing.
(Note to myself - find space in garage for milling machine and buy one!)

Ian.

You know it makes sense........ 

Some pictures of the progress:

Nice! 

That's a lot more progress, than I've managed. Since before Christmas Eve. 

The most comforting thought..... The hardest part, is behind you now. Mebbe! 

David D

[awemawson]

Oh dear . . now you are HOOKED 

Yes you NEED that milling machine, after all EVERYONE needs a milling machine, but that's just the start, next it'll be a shaper or some other machine, then before you know it it'll be an extension on the back of the garage 

It's an addiction - I should know I'm addicted 

[vtsteam]

And, of course, a second tiny shop......

wait, back to no mill again.............nooooooooo!   

Beautiful job on that -- more shapely! And all hand work. I bet some day you look back on that engine and are proud of that even with a shop full of newer machines. 

[ian_in_the_midlands]

Is this the sort of fuel people are running their flame lickers on:
http://www.ebay.co.uk/itm/141522876949?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
(Isopropanol 99.9%)?
If not, what should I use that is available in the UK without a licence?

Is something like this a suitable wick:
http://www.ebay.co.uk/itm/Wick-Round-Pixie-5-32-1M-length-4mm-x-1000mm-Cotton-Made-in-England-/261705625530?pt=UK_Home_Garden_Lamps&hash=item3ceedeefba

[Stilldrillin]

Hi Ian.

Have a look in your local hardware store, for methylated spirits. It will do the job.

I now use this, as "meths"........ http://www.ebay.co.uk/itm/181622131173?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT   (Though, the offer was for 1 bottle at a time).

Use stove rope, as wick. It doesn't burn away....... http://www.ebay.co.uk/itm/Stove-Rope-Gasket-Seal-for-Flues-Woodburner-Stoves-Door-Glass-Fire-Seals-/320873562369?pt=UK_HG_FireplacesMantelpieces_RL&var=&hash=item4ab58e0101

David D

[Manxmodder]

David, just out of interest,will the ethanol produce less water vapour than the purple meths that we get from the chemist/drug store?   And I wonder which of these fuels burn hotter?.....OZ.

[ian_in_the_midlands]

I had read somewhere not to use meths because it produces more moisture and does not burn so hot.
I had not seen the bio-ethanol before. Would this be better than Isopropanol 99.9%?
Isopropanol would have other uses in addition to being a fuel (Cleaning PCBs etc).

I had not thought of using stove rope.

Thanks.

[Stilldrillin]

David, just out of interest,will the ethanol produce less water vapour than the purple meths that we get from the chemist/drug store?   And I wonder which of these fuels burn hotter?.....OZ.

OZ.
Yes. But.......

I find "meths", quite adequate, for test purposes/ cleaning etc.

Running a burner under a steam engine boiler, will produce sooting, after a session.
A small flame, to test an engine for a few minutes, will not be noticeable.
I've never noticed water vapour, from a flame. My recent problems were caused by warming the sheer mass of the  castings.

When it comes to showtime, and several hours running. I find the denatured alcohol is much less sooty, and hotter.

A pal, with more experience than me, advocates shellac thinners. Though, I've not managed to locate any, as yet.

I always think. Schoolboys managed very well with what was available at the time.
Mum's sewing m/c oil, and a medicine bottle of meths, filled at the chemists, (for a shilling)........

I think, it's better to develop, over time, and experience, what suits you and your engines.

David D

[Stilldrillin]

I had read somewhere not to use meths because it produces more moisture and does not burn so hot.
I had not seen the bio-ethanol before. Would this be better than Isopropanol 99.9%?
Isopropanol would have other uses in addition to being a fuel (Cleaning PCBs etc).

I had not thought of using stove rope.

Thanks.

Ian.
See above.......

Isopropanol/ bio-ethanol....... I dunno!

All I can suggest, is to buy a bottle of one of them. To establish a benchmark.
Then, over time, you can try others. To decide, what suits you, and your engines........

Stove rope, is made of glass fibre. It doesn't burn away, but it is loosely woven, and unravels at it's cut end.

I use a smaller diameter, with the cut ends bound with a couple of turns of copper wire.
Then  install it as a loop, with the ends inside the tank......




David D

[Manxmodder]

This is my method.

Piece of dowel. Minus a thou or so, on bore size.......




Smear of fine grinding paste. Plus oil, as time goes on. Around 80rpm.......




The cylinder is oscillated backwards n forwards. Reversing occasionally on the lap. Until all feels smooth with no tight spots.

Works for me! 

David D

Hi David, I used your wooden lap and fine grinding paste technique to good effect whilst finishing a critical bore size in a bronze trunnion block for the old Alba shaper I'm rebuilding.

I made it from a piece dried ash firewood and it worked remarkably well
......OZ.

[fcheslop]

Poppin will run fine on meths
dunno who told David to use shellac thinners.
She is looking well

[Stilldrillin]

Hi David, I used your wooden lap and fine grinding paste technique to good effect whilst finishing a critical bore size in a bronze trunnion block for the old Alba shaper I'm rebuilding.

I made it from a piece dried ash firewood and it worked remarkably well
......OZ.

Nice one, OZ!   

Very pleased it has helped.......   

David D

[Stilldrillin]

Poppin will run fine on meths
dunno who told David to use shellac thinners.
She is looking well

Yabugga!

[chipenter]

Shellac Thinners is white meths it's hard to come by as people drink it .

[fcheslop]

 
Any good trade outlet's.
Theres one at Thirsk the names slipped my memory
It wont matter as poppin runs well on meths .
cheers

[ian_in_the_midlands]

A bit more work with a saw and a file on the standard.
If the engine runs I will polish it up, but for now I need to move on.

Put together the parts so far.

If I spin the flywheels they will turn for 15 seconds before stopping.
Is this acceptable of should I be expecting better?

Unfortunately there the crank now looks to be a little off true, causing one flywheel to wobble a bit.
I will continue with it for now

I also made up a temporary burner for trial purposes.

[Stilldrillin]

Ian.

I guess, you haven't made the valve mechanism, as yet.

Even without it. A 15 seconds spin, is fantastic! 

With, the valve mech in place. 15 turns would be good...... 

I think, you're a bit enthusiastic with the spare wick!
Only need sufficient, to loop once, around the base of the tank. Save some for another day....... 

Looking good. Shaping up well! 

David D

[vtsteam]

Yes it is looking very nice, indeed!

[ian_in_the_midlands]

I thought if I put the wick in there I would know where to find it in the future. .

[Stilldrillin]

I thought if I put the wick in there I would know where to find it in the future. .

Ah!

I'd not thought of that....... 

David D

[vtsteam]

I once saw a tapeworm in a jar of formaldehyde, and.......well, I'm getting dejavu....

[ian_in_the_midlands]

Disaster looming!
Not much done the last couple of weeks as it has been too cold in the garage.
Had a look at it today and noticed the threads tapped into the cylinder to attach it to the standard appear to be breaking up. The bolts that were originally all a good tight fit are now very lose.
I have been very careful not to overtighten the bolts so am not sure the cause.
The plans call for an imperial thread, but I used metric. Maybe the thread is too fine to hold in cast iron?
It is happening on all 4 tapped holes.

I can not drill out and go up a thread size as there is not enough metal, so need another solution.
I thought maybe rather than using bolts, I threadlock some studs in, but suspect that threadlock may not withstand the heat.

Anyone else with any suggestions as to why this has happened, and the best way I could overcome it? I really do not want to have to build the cylinder and piston again, especially as I do not know how to avoid the same thing happening again.

[Stilldrillin]

Oh bugga, Ian. 

I would go with the stud and threadlock idea, to stabilise the remaining threads.

I have used Loctite 270, for many years.
Even for steam engine (exhaust) pipe joints, and hot air engine displacers. Never had a failure........ 

David D

[awemawson]

Loctite 270 is down to less than half it's strength at 150 deg C and the makers don't push their graph beyond that temperature !

[Stilldrillin]

Loctite 270 is down to less than half it's strength at 150 deg C and the makers don't push their graph beyond that temperature !

I'm sure, they used to quote 250 deg!

I've used it for many years, without problem.........

Everyone. Make your own mind up. 

David D

[awemawson]

Relevant graphs are on page 2

http://www.farnell.com/datasheets/22660.pdf

They quote 250 deg C as the temperature to raise it to to break the joint

[ian_in_the_midlands]

What sort of temperatures is the cylinder likely to reach?

[Stilldrillin]

Relevant graphs are on page 2
http://www.farnell.com/datasheets/22660.pdf

They quote 250 deg C as the temperature to raise it to to break the joint

You are quite correct, Andrew! 

But, I would be happy to use, what I have always used. In this small, lightly stressed application........

David D

[Stilldrillin]

What sort of temperatures is the cylinder likely to reach?

At the standard end. Not much, above the temp of boiling water. If at all.......

David D

[fcheslop]

Will it not be possible to simply drill the holes deeper and rethread?? or drill and tap the frame for a couple of grub screws to lock the cylinder into the frame.
What size did you use 2mm
cheers