The Workshop Progress thread 2018

[David Standing 1Participant @davidstanding1]

Posted by geoff walker 1 on 22/06/2018 09:51:08:

It runs very well Jim, a lovely model, excellent detail.

Just looking at the flywheel which I assume is cast iron, super outer rim finish, what's the secret?

What does a stroke of 15mm by 20mm mean?

Geoff

It means the cylinder is 15mm inside diameter (bore), and the piston has a travel of 20mm (stroke).

[HopperParticipant @hopper]

Bit late I know, but maybe early for next time. An old painter's trick when prepping aluminium or galvanized steel etc. is to wipe it down with white vinegar. It cleans and etches the surface and helps the paint stick.

[Jim NicParticipant @jimnic]

Geoff

To achieve the distinctly non prototypical polished rim on cast iron flywheels, after machining them to size and painting them, I mount them on a mandrel the same diameter as the crankshaft and chuck them up in a 3 jaw chuck on the lathe. Then it's a matter of turning it at a slowish speed (250 – 300 RPM ) and using a file and then progressively finer grades of abrasive paper until a smooth finish is obtained and finally finishing off on a buffing wheel.

Before I made my buffing wheel I left them on the lathe and used Solvol Autosol automotive metal polish. This is not recommended, being a bit risky in the event the polishing cloth catches in the chuck.

Jim

Edited By Jim Nic on 22/06/2018 14:07:19

[JasonBModerator @jasonb]

Over the last week I have been doing the odd bit of machining on the Robinson hot air engine's base, started life as a slice off some 100mm dia bar

Then after a twirl or two on the rotary table and much swarf later it looks more the part. I'm quite liking the 150mm Rotary Table that ARC do, the 72:1 ratio makes for less handle turning and the ability to set the ring with 0-360 degree divisions anywhere around the table makes for easier setup, numbers are also easier to read than my Soba one.

And with cylinder and crank/bearing in place

[Jim NicParticipant @jimnic]

"A twirl or two on the rotary table". I really must read up and practice twirling if that's the kind of result possible.

Jim

[mechman48Participant @mechman48]

Twirling or twerking?… ooh matron you are awful… ​… super finish on your flywheel by the way, now you've described your method I've packed that one away into the 'memory bank'….Hmm if I don't forget where that is…

George.

[duncan webster 1Participant @duncanwebster1]

Today I set about making blow down valve for my stationary boiler, and while I'm at it a second one, for the loco I'm building (very slowly) at the same time. I know the thread in the boiler is 5/16*32 so no need to check. Wrong, it's 3/8*32, so I'm now making 3 off. It takes surprisingly little extra time to make 3, finding all the right drills, taps etc takes most of the time.

Artificial intelligence is no match for natural stupididty!

Edited By duncan webster on 24/06/2018 00:03:08

[Michael BriggsParticipant @michaelbriggs82422]

Arc 150mm rotary table, £389, ouch ! 😳

[NigeParticipant @nige81730]

Mmm, WARCO do a 150mm rotary table for £149 but I'm not experienced enough to make anything other than a 'cost' comparison though the Arc one certainly looks a more expensive job.

Just thought this might not be the right thread to kick off a comparison of rotary tables, would a moderator please move if necessary.

Edited By Nige on 24/06/2018 08:24:01

[mechman48Participant @mechman48]

A little more done on my Vertical Cross, cladding & banding… may have to trim banding a little more, it clears the inlet flange ok, possibly trim the length a touch more, I leave the masking tape on to ensure paintwork has hardened up plus allowing for any touch ups… looks ok with the light blue…

George.

[geoff walker 1Participant @geoffwalker1]

Hi Jim,

To achieve the distinctly non prototypical polished rim on cast iron flywheels, after machining them to size and painting them, I mount them on a mandrel the same diameter as the crankshaft and chuck them up in a 3 jaw chuck on the lathe. Then it's a matter of turning it at a slowish speed (250 – 300 RPM ) and using a file and then progressively finer grades of abrasive paper until a smooth finish is obtained and finally finishing off on a buffing wheel.

Yes this method was great Jim. I've just done a stuart flywheel finishing with 1200 grade wet or dry using light oil as a lubricant.

A final buff and it's come up a treat.

cheers Geoff

[mechman48Participant @mechman48]

… 'Yes this method was great Jim. I've just done a Stuart flywheel finishing with 1200 grade wet or dry using light oil as a lubricant.' …

​I've just polished up the flywheel for my Vertical Cross today using the above method ( inc.1500 grade ) & it has turned out very nicely, not a mirror finish, but far better than machined cast iron.

George.

[Neil WyattModerator @neilwyatt]

Hey Gerge, I like the Origami bird…

I have one of the 150mm Warco tables, strictly far too huge for my X2, but I needed a big one and it just about lets me get away with it.

Very smooth and nicely made, I thought a lot for the price.

I know Jason is very chuffed with his Arc one which is a lot more 'modern'.

[mechman48Participant @mechman48]

… Hey George, I like the Origami bird…

… One tries!

[mechman48Participant @mechman48]

Did a pre-run reassembly, looks ok if I say so mesel', just need to reset timing & bit clean up…

Bit of polishing up on Flywheel…

Re-assembled …

George.

[Johnboy25Participant @johnboy25]

It’s been a little too warm in the workshop lately to get serious work done.😕 Yesterday my max/min thermometer indicated 31 Centigrade. As much as I like this time of year I seem to more done when it cooler. So it’s evenings and mornings being the best times at the moment. A good time perhaps to draw up plans for an insulated replacement workshop!

John

[Jim NicParticipant @jimnic]

Certainly looks good George, do she run yet?

Jim

[mechman48Participant @mechman48]

Posted by Jim Nic on 29/06/2018 13:54:58:

Certainly looks good George, do she run yet?

Jim

​She do… albeit a tad noisily, had a pee about getting the timing right… again! but it's sorted, am sorting the video out onto you tube my channel so will link onto here… hopefully

​George.

[geoff walker 1Participant @geoffwalker1]

Yes, very nice George.

Do you run on steam or compressed air.

Could I ask a general question here.

A lot of "older" designs have a crank arm which is very simple and not balanced with a web the opposite side to the crank pin.

Why is that, do some engines just not need it?

Geoff

[mechman48Participant @mechman48]

Re-assembled & trial run… hopefully it has embedded her ok. Still need a tidy up & clean up but she's working…

George.

[JasonBModerator @jasonb]

Looking good George but does sound like you are leaking air which would be one reason your compressor is kicking in so soon.

J

[Jim NicParticipant @jimnic]

Good work George, well done.

The problem you have now is what to do next!

JIm

[Jim NicParticipant @jimnic]

Geoff

I think that model engines at this scale running at representative speeds don't need balancing weights on the crank. However, for appearance sake sometimes they are included.

Here is my Potty Vertical Cross with a balancing extension because the piece of steel I made it from was big enough to do it and the cut off excess would just have ended up in the waste bin.

Jim

 

Edited By Jim Nic on 30/06/2018 10:56:42

[mechman48Participant @mechman48]

Posted by JasonB on 30/06/2018 07:01:07:

Looking good George but does sound like you are leaking air which would be one reason your compressor is kicking in so soon.

J

​Thanks; Yup! I suspect it is passing spool valve… clearance not close enough between cyl bore ID & spool v/v OD even though bore was 'reamed'. Apart from stripping it out 'again' it is a runner so methinks I'll leave well alone for now & give the grey matter, & my patience a break.

G.

[mechman48Participant @mechman48]

Posted by Jim Nic on 30/06/2018 10:47:13:

Good work George, well done.

The problem you have now is what to do next!

Jim

Thanks, will step back for now & look through plans for next project.

Geo.

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