Ohrndorf 5 Cylinder Radial

[petertha]

CC cleaned up a bit, nearing completion

[Vixen]

Hello Peter,

Top marks for persistence.          I suspect I would have given up before the third attempt.

As for Alum to remove broken taps  It's usually credited as being the way to go . Now; having tried it several times, without success, I believe it is just an 'old wives tale' which is repeated time and time again by those believers, who have not actually quite got it to work.

Radial engine are a lot of repetitive work. Just stick with it.

Mike   

[ozzie46]

Actually I usex the alum trick when I made my "Mastiff" engine and it worked great. Used a teflon pan, kept the alum mixture saturated and the tap evaporated into bits. No discoloration to the aluminum part.

Ron

[Vixen]

I stand corrected.

It never worked for me, I only got discoloured aluminium with the broken tap unmarked and intact. Maybe there is more than one substance being sold as 'alum'.

Was it a carbon steel tap or a high speed steel tap?

Mike

[Roger B]

There are a range of different Alum compounds. Alum alone usually refers to potassium aluminum sulfate KAl(SO4)2·12H2O. I have also used this to sucessfully remove broken HSS taps from brass aluminium parts. It requires time, some heat and some agitation to ensure that there is fresh alum solution in contact with the tap. It has no effect on carbide taps. I don't know if the type of aluminium also has an effect 

The picture is what was left of an M2 tap that was broken in a big end cap after alum treatment. It also took the marking blue off the cap.
 

[Vixen]

Hello Roger

Where did you source your potassium aluminum sulfate KAl(SO4)2·12H2O? Was it from a chemicals firm?

E-bay may not be the best place to buy it. The product descriptions are not always as reliable as we would like.

Mike

[Roger B]

Hello Mike,

This came from the lab at work so I am fairly certain that's what I got.

[Vixen]

Hello Mike,

This came from the lab at work so I am fairly certain that's what I got.

Ha ha,  I think I would trust your lab at work any day, compared to the e-bay sellers.

Do they take outside orders????

Mike

[ozzie46]

I stand corrected.

It never worked for me, I only got discoloured aluminium with the broken tap unmarked and intact. Maybe there is more than one substance being sold as 'alum'.

Was it a carbon steel tap or a high speed steel tap
Used grocery store alum.

Mike

HHS tap.
Ron

[petertha]

Questionable grocery store alum may have been part of my issue. Another factor may have been this particular tap. It had a coating which may have provided a permeability barrier to inhibit chemical action? The tap is suited for aluminum & cuts like a damn. But all bets off if you drive any kind of tap into the celler. Initially there was an encouraging stream of bubbly-bubbly's coming directly from the tap shrapnel top, possibly acting only on the exposed core metal? I really don't know. I've seen YouTubes where much larger (I suspect conventional bright HSS) taps were fizzed out in no time & native part looked no worse for wear. I treated time lapse YouTube video as one step more believable over well meaning, but likely unproven recipes of Grampa's surefire pickle juice concoctions.

FWIW, after this episode I made a rudimentary coring plug cutter from O1. My edge was just hand ground with a Dremel, but the basic idea was like an annular cutter. Unfortunately without nice sharp sidewall flutes, just reduced diameter for clearance. We're talking only 3mm nominal here. I simulated a broken tap with a pin sticking out of the hole. I peck drilled the material with WD-40. It did make progress, I went in about 0.2" & got bored. I think this might better with proper edge grinding. Maybe even a single edge D-bit principle? The idea is drill out the surrounding area to base of tap & avoid dealing with the tap altogether. Dress the hole, insert tight fitting plug of native material with Loctite or whatever & never tell anyone.

[Admiral_dk]

Your crankcase looks very nice - shame about the mishap .... 

I must admit that I don't see any real reason for not drilling the holes all the way through .... other than the builder knows it's done ....

On a full size it will help preventing it from 'sweating oil' - but I can't see this with this model that has a vacuum in the crankcase.

Another subject - ball bearings works best with an oil mist to lube them ..!!.. no mention of it being mixed with fuel - but the most durable Danish moped from my youth was a single speed SCO where the whole engine and gears are inside the crankcase and lubed from the gasoline / oil mix (5%) and they regularly ran more than 250,000Km. before any rebuild.
So I'm not sure that having a seperate oil section for the cam-box is necessary .... but I will not claim that it's a bad idea either ....

Best wishes

Per

[Laurentic]

Per - there is not just the ball race in the gearbox/cam section there are also the gears and the cams.  It was to ensure that these were well lubricated that on my 3 cyl radial I went for a separate section (from the crankcase) with an oil bath, perhaps Peter had the same reasoning I don't know.  Different ships different splices as the saying goes, not to say either way is right or wrong, just the way one sees it!

Chris

[Vixen]

Chris,

My five cylinder 40 cc Seidel ST540 radial engine does not have a separate oil bath for the gears and cam section, it uses the oil mist in the fuel (10%).

My big, 350 cc, Bristol Mercury engines have a wet sump and the oil bath arrangement for the cam and gears.

Seems either arrangement can be made to work.

Mike

[Laurentic]

Mike - exactly! 

Like I said,  "Different ships different splices as the saying goes, not to say either way is right or wrong, just the way one sees it!"

You pays yer money and yer takes yer choice - as another saying goes!!

Chris

[Vixen]

 
Mike