Minnie 1″

[Ron OlmsteadParticipant @ronolmstead92388]

Following, got the drawings and book. Contemplating starting my own minnie.

[james huxstepParticipant @jameshuxstep40895]

ok so……

Ive started on the front assembly, smokebox etc while i get brave enough to solder the boiler together.So far so good smokebox/ring/door chimney casting done and fitted and divided for the 1/16" rivets. Onto the steel section at bottom of smokebox which holds the front axle fork. Achieved a nice radius in the 1/16" steel to match smokebox od for the base of the box section under the smokebox. Onto the box section itself, made a nice radiused former to bend sheet mild steel over [compensated in width to bring the final width once formed to the 1" required]. Achieved a nice 90 degree bend in the sheet mild steel but not at the radius i filed, not far off but if i continued it would have made the component drastitically overwidth.

Is this the minimum bend radius for 1/16" plate?

Do i anneal the steel sheet? [ [i know this is not as easy to do as sheet copper or brass]

Do i measure radius formed with a radius gauge and edit the former accordingly?

thanks

james

ps i have photos of progress if anyone is interested.

[Harry WilkesParticipant @harrywilkes58467]

Posted by james huxstep on 10/03/2020 14:06:14:

ok so……

Ive started on the front assembly, smokebox etc while i get brave enough to solder the boiler together.So far so good smokebox/ring/door chimney casting done and fitted and divided for the 1/16" rivets. Onto the steel section at bottom of smokebox which holds the front axle fork. Achieved a nice radius in the 1/16" steel to match smokebox od for the base of the box section under the smokebox. Onto the box section itself, made a nice radiused former to bend sheet mild steel over [compensated in width to bring the final width once formed to the 1" required]. Achieved a nice 90 degree bend in the sheet mild steel but not at the radius i filed, not far off but if i continued it would have made the component drastitically overwidth.

Is this the minimum bend radius for 1/16" plate?

Do i anneal the steel sheet? [ [i know this is not as easy to do as sheet copper or brass]

Do i measure radius formed with a radius gauge and edit the former accordingly?

thanks

james

ps i have photos of progress if anyone is interested.

Pop them in an album we can all take a look 👍. i/m maybe a bit premature but if you have not I'd do some research on the fitting and placment of the water pump.

H

[james huxstepParticipant @jameshuxstep40895]

OK will do.

I have machined the pump pad, but that is as much as I have done on that.

Thanks

James

[Brian AbbottParticipant @brianabbott67793]

Hi James.

I have taken loads of photos whilst building my Minnie, just shout if you need anything.

[james huxstepParticipant @jameshuxstep40895]

Hi thanks.

So what would you suggest for the axle fork box under the smokebox? Edit the radius for bigger on the former accordingly,or anneal the 1/16" steel to try and match the formers existing smaller radius?

Thanks

James

[Brian AbbottParticipant @brianabbott67793]

Hi James.

I just bent the 1/16 plate in a vice between two blocks, then soldered to the curved section.

No real point annealing as it doesn't make a great any difference with mild steel.

Edited By Brian Abbott on 10/03/2020 15:55:30

Edited By Brian Abbott on 10/03/2020 15:55:42

[james huxstepParticipant @jameshuxstep40895]

Very nice!

In the vice between two blocks of steel,or wood?

Thanks

James

[Brian AbbottParticipant @brianabbott67793]

Two blocks of steel, just in the vice, I had to overhang the edge of the vice for the second bend.

Just file a radius on the block and tap it round.

[james huxstepParticipant @jameshuxstep40895]

Cheers mate,I'll give that a try. I'll keep you posted

Thanks

James

[james huxstepParticipant @jameshuxstep40895]

Well success!

Talk about making things harder than they need to be.A few encouragements with a rubber hammer using the steel in the vice plan, worked a trick.

Thanks for all your help guys!

james

[Brian AbbottParticipant @brianabbott67793]

Sometimes we overthink these things.

Good luck with the build.

[james huxstepParticipant @jameshuxstep40895]

ok, so i have achieved the whole axle box assembly+bush front and back plate and machined the chimney base. Tomorrow im looking at making the two holes under the chimney base casting in the smokebox itself. The 3/4" one and the smaller one to the side for the blower fitting. Now i know from past experience that copper is very grabby. Should i put a centre drill in and then straight to the 3/4" drill, or centre and then a range of drills ramping up to eventually the 3/4" drill.?

thanks

james

[pgk pgkParticipant @pgkpgk17461]

I needed an accurate hole in the side of a twin gang plastic back-box yesterday. OK not as grabby as copper but i chose to drill a central through hole and then go with an endmill to size.

pgk

[JasonBModerator @jasonb]

I think an ordinary twist drill will end in tears. A step drill will be a lot less likely to snatch or if you have a boring head than that would work well, failing that a 6" half round file won't take long for the larger hole and then the step drill, ctr cutting milling cutter or round file for the blower clearance.

 

Edited By JasonB on 25/03/2020 19:26:15

[james huxstepParticipant @jameshuxstep40895]

OK thanks for the assistance. A set of step drills ordered,so hopefully all will be fine with that.

Any ideas on how to turn the chimney casting? I get all the basic turning bits,its the whole centring it to run concentric with the inner bore. The book suggests making plugs for either end but my ally casting does not have any holes in either end.

Also how's best to turn aluminum?

Thanks

James

[JasonBModerator @jasonb]

The wooden plugs are only to fill the holes so you can mark out the ends. Post a photo of your casting and I'll suggest a way forward as you will have to bore it out from scratch.

[james huxstepParticipant @jameshuxstep40895]

Edited By JasonB on 29/03/2020 20:33:47

[JasonBModerator @jasonb]

Will get back to you tomorrow.

[JasonBModerator @jasonb]

I think I would start by lightly filing the top end to give a flat surface for marking out on, swing 4 arcs of approx half the diameter in from points around the edge and then place a punch mark where the middle is likely to be much like whats shown in this image

Now holding the casting by the flange in the 4 jaw chuck get the bottom and top punch mark to run as true as possible then at a slow speed drill with a ctr drill. Bring up the tailstock for support and turn the top parallel section to 1 1/16" and lightly face the end as far in as you can reach without hitting the tailstock ctr.

Reverse the casting around and now gripping by the top parallel section ctr drill the bottom end and again bring up the tailstock ctr for support. Face the end and then the outside of the flange followed by the 31/32" collar. Then taper turn the outside.

Remove the tailstock and fit the fixed steady to run on the 31/32" diameter to support the casting while you drill it out to 3/4".

Reverse the work once more so you are holding by the OD of the flange and set the fixed steady to run on the 1 1/16" top section. You can now bore out the inside to the correct taper.

[james huxstepParticipant @jameshuxstep40895]

Thanks very much Jason,I'm half way through.so far so good.for the outside taper do I match the castings existing taper,or do I work it out from the drawings?

Thanks again

James

[JasonBModerator @jasonb]

I'd work it out from the drawings and then see how that compared to the casting and adjust if you need to.

[james huxstepParticipant @jameshuxstep40895]

ok, thanks jason, that went pretty well.There is a couple of small holes in the casting i found whilst machining but otherwise all good.

A quick question about hss endmill/slot drill speeds.I seem to be ok with the larger and medium side of end mills/slot drills, but small end mills tend to be a bit hit and miss.i.e. the 1/16" slot drill i just broke.i wonder if im not running them fast enough rpm wise.I always slow down the feed rate on the table feed motor and keep to light cuts. i am running the 1/16" slot drill at about 1100 rpm. I seem to fair slightly better with the 4 fluted type, but tiny diameter anything tends to be a bit hit and miss for me .All machining cutting fluid is used.

Any thoughts anyone?

thanks

james

[JasonBModerator @jasonb]

You don't say what material but that is too slow, Ideally in steel you would want about 6000rpm and aluminium anything upto 12000rpm but will probably have to be limited by the max speed of your machine.I'd hand fees on the small sizes so you get a bit of feel. Depth of cut with those small slot drills one quarter of diameter.

[james huxstepParticipant @jameshuxstep40895]

Thanks for the assistance on milling speeds, yeah i was running too slow. ive since solved that issue by doubling the speed and taking smaller cuts.

Quick question.I need to create the reamed hole 1/4" in the axle fork. i have a new hand reamer 1/4".What size would you drill under sized before reaming with the reamer? also can i put the hand reamer in the drill chuck as it has a parallel shank., and do it under power?

thanks

james

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