By continuing to use this site, you agree to our use of cookies. Find out more

Member postings for geoff walker 1

Here is a list of all the postings geoff walker 1 has made in our forums. Click on a thread name to jump to the thread.

Thread: SX2p mill gas struts
25/02/2019 16:08:58

Hi John

I used 120n on mine which easily supports the head and doesn't offer too much resistance


Thread: Green Twin Oscillator - 2019 Update
18/02/2019 11:44:01

Hi Jason,

Thanks for your reply. I thought about the pipes coming sideways but would prefer to have them exiting from the underside of the valve block then down through holes in the base into a hollow plinth where there will now be ample space for the pipework, to link the blocks. All the pipework will be concealed apart from a short inlet and exhaust pipe.

I am making the blocks muncaster style with two semi circular grooves as shown in the picture.


I really must open a build log on this engine, will do when I get back from holiday.

Thanks again Geoff

16/02/2019 14:21:53

Hi Pat,

Thank you for your P.M., I'll get back to you on that.

Really glad you posted the video. I was have having a real problem arranging the pipe work for my engine.

Referring back to my earlier post you have given me the answer.

By switching the port and pivot blocks around, which I can do, I will have ample space to arrange the pipe work and be able to use compression fittings.

With the port blocks inside of the cylinders space was very tight.

Thanks again Geoff

14/02/2019 09:19:03

Hi Pat,

This side of the pond is good, a little cold but gradually getting warmer, assume you live stateside.

Nice model well done, runs well.

I am currently making a twin cylinder d/a oscillator with a similar configuration to yours using a central cast iron flywheel and cylinders cast in iron from home made patterns. Unfortunately I don't have foundry like yours!!!!

Could I ask is there any particular reason that you have the port blocks on the outside of the cylinders and the pivot blocks on the inside? My plan is to do it the other way round.

Also what size is your engine, i.e. stroke length, bore size etc.

cheers Geoff

Thread: Jason's Firefly .46 Build
11/02/2019 18:26:38

Hi Peter,

If you are making a new liner and presumably a new piston then it might be of interest to you to have a look at the website referred to in an earlier post by Ian Hewson

The site is Adrians model aero engines. In the technical topics section there is an excellent article by a guy called Ken Croft on cylinder liners and pistons including lapping and fitting.

I found it really interesting, maybe you will too.


Thread: Boyes of York, good value
08/02/2019 13:09:13

Hi All,

We had a very enjoyable weekend in York recently.

While there I called in Boyes. Never heard of the them before but apparently they are discount chain in the North.

I picked up a set of small HSS drills. 20 in total from 0.3mm up to 1.6mm. Cost about £2.50 for the set, and they're ok, I have used a couple, only on non ferrous but they feel good.

Also picked up a set of 5 needle files all with small soft feel handles, about £3.

Worth a look if you have a Boyes store in your area.


Thread: Jason's Firefly .46 Build
07/02/2019 19:43:49

Hi All,

Dismantled the firefly yesterday for a winter service.

My "pilot", John, a friend and experienced aeromodeller felt that the engine was starting to labour over the few months of flying. I wasn't really surprised because it's been worked hard over the last year.

I was surprised when I opened it up and discovered the wear in the con rod. The big end hole was elongated by a good 0.010" so much so that the underside of rod had been rubbing against the crankcase. The small end was also a sloppy fit. I'm curious as to why it has worn so much. I used H15 alloy as specified and the crank and gudgeon pin were polished before assembly two years ago. Both ends had lubrication holes to feed the bearing surface. Is this sort of wear to be expected from a plain con rod with no additional bearing material?

Anyway using my new super dooper Seig mill it was a simple task to open the holes up and insert slimline phosphor bronze bearings. You can see the renovated rod in the photo. Let's hope they stand up better than the plain alloy bearing, time will tell.



Thread: Hip replacement - End of live steam?
04/02/2019 15:35:01

Yes, good for you sir! you're looking good

Hunslet looks great as well.


Thread: M Type Apron Direction
04/02/2019 11:49:56


I would agree that switching between lathes with a different handwheel feed rotation is certainly NOT recommended.

A friend of mine had his drummond M type for 40 years using the factory hand wheel feed set up.

He got a casting of me and did the conversion you see in the earlier post. He said after 1/2 hour using the apron he didn't even have to think about which way to turn the hand wheel even after 40 years of turning it the other way


04/02/2019 11:33:53

Hi Ian,

Picture below of the mew issue 234 conversion.

If you have a go, don't buy the gears from Muffets like I did, very expensive. Use either Boxford or Myford change wheels and modify them, i.e. change the hole size by bushing the existing hole. Lot cheaper way.

I also made a pattern and had a complete new apron cast for the myford, lot of work but neat with the gears enclosed inside.



Thread: Jason's Firefly .46 Build
24/01/2019 22:37:46

Hi Ian,

Good luck with the rest of your build.

I made two pistons for my firefly. The first one I made a poor job of lapping it into the liner. The engine ran but lacked power and when used on a model aeroplane it just had enough power to "limp" into the air.

With the second piston I made sure it had a good square leading edge and I only lapped it up to TDC. The first piston I lapped right up to the end of the liner which was a I feel the mistake I made.

If you do some calculations you will see that TDC is 0.8 mm below the underside of the cylinder head boss. I lapped up to that point and it made a big difference to the compression and the power output.

Just my thoughts Ian, hope they are of interest


Thread: Small Milling/Drilling Spindle (again)
08/01/2019 18:58:25


As you are very limited on space ... I would make the body from good cast iron, or bronze, and turn the bearing surfaces directly into it. Preferably a double cone each end [as per the classic watchmaker's lathe headstock bearing]; but realistically, I'm sure a single cone each end would do nicely.

Plain cone bearings tend to 'bed in' rather than wearing out.


Michael, I'm also liking your idea for cone bearings into bronze. Any idea of the best angle for such cones?


In the potts article, MEW 73 the included angle is given as 8 degrees. It has a double cone at each end as per Michaels suggestion.


07/01/2019 19:53:14

Hi steve,

MEW issue number 73 has a article on a re designed Potts milling spindle..

The spindle and the housing have been modified, based on a illustration in a watchmakers book by Donald de Carle.

Looks very tricky to make but the author of article maintains it would be very accurate and suitable for high speed work.

It uses double opposed cone plain bearings. It is slimline design and like I say not easy to make but it may be of interest to you.

I have a copy of the magazine. You can have it for postage (paypal £2).

Message me if you are interested


Thread: small cast iron flywheel
18/12/2018 12:54:42

Hi All,

With reference to the last post, I bought a Stuart flywheel.

A little smaller at 3 1/2" but should do the job.

Not sure how to hold it for machining as there was not an extended boss in the centre.

Used the method shown below. Perhaps a bit long winded but worked well.

The plywood disc has a square shoulder turned and the diameter is a snug fit on the inner rim of the casting, tapped it on with a copper mallet up to the shoulder.




Thread: Jason's Firefly .46 Build
11/12/2018 13:46:13


If you don't want to make a stepped broaching tool you could make a keyed driver instead.

I made one for my firefly. you would of course have to mill a keyway slot in the crankshaft.

If you go back to page 5 in this thread you will see the driver and crankshaft with the key fitted in my parts photograph.


Thread: Interests other than Model Engineering
04/12/2018 07:20:42

Football, cricket and golf, in that order.

I played football until I was 35, cricket until 55 and golf I started at 11 and still playing.

The latter is the main reason why I make such painfully slow progress with my model engines. I spend far to much time honing and fine tuning my golf swing instead of honing and fine tuning my engines. My choice though, I only have myself to blame.


Thread: Steam Engine Number One
25/11/2018 11:11:50

Hi Iain,

One last post from me with a diagram I did last night.

As I understand it, you have a cylinder whose bottom hole is s slidefit for the piston ron and the top has a registration plate which fits into the underside of the plate.

Not quite like above Iain the piston rod guide is separate from the cylinder. The register is on the underside of the top plate.

Have a look at the jepson drawings on and also the drawing with this post.

Hope it helps you Geoff see also the photos of the cross head

20181125_103346 (2).jpg



Thread: Morse taper sleeves
24/11/2018 11:01:59

Hi Larry,

All that matters is that it fits the gap between the sleeve and the arbor. ????

Don't quite follow the above Larry. I can vaguely see what your doing, the split collar forms a rigid face which you drive wedge against but not how it's actually used.

Now you have hang of posting pictures how about some more showing the clamp in use, I'd be interested


Thread: Jason's Firefly .46 Build
24/11/2018 10:52:34

Well done Peter,

I'm glad I'm not only one who made mistakes making this engine.

I eventually took mine apart re lapped the bore and made a new piston and con rod, to improve the performance. I cu'd the lapping of the piston into the bore first time round, second piston was a much better fit.

How about some pictures of your engine, love to see some


Thread: Steam Engine Number One
22/11/2018 15:45:53

Hi Iain,

I have been looking at your plans. This engine is similar to one I made last year.

Could I make the following suggestion regarding cross head design which you may wish to consider.

Your first drawing shows 2 cross bars which support the cylinder block. Why not replace this with a plate across the top. This plate would have a hole in the centre for the piston rod guide. The top of the piston rod guide would locate in the bore of the cylinder and that would of course register the position of the cylinder.

The under side of the plate would need a female register turning which truly concentric with the hole in the centre. The cross head guide is made from square stock turned round for most of it's length. On the top of the cross head you would need a male register to match the one in the plate.

Here a two pictures from my picture flle, Jepson Engine. Geoff


20170816_123316 (2).jpg

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Meridienne oct 2019
Eccentric July 5 2018
TRANSWAVE Converters
Eccentric Engineering
Allendale Electronics
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest