pacomb

Hello all,

I suppose some of you will say I am talking about such an old engine that it´s not useless, but I really hope someone can help me.

I have a JPX 240 turbine, wich has been my dream engine since many years ago, 15 years?? It is dismantle as the bearings where damaged. That is how I buy it. I am really concern because I find different answers to this issue. As far a I know, the internal diameter of the bearing is 10,16mm but no one seam to have this measure. Called boca bearing and they have no idea. The only measure they have is 10x6x8 at $359 the pair (whoooo!!!!)

Making a web search I found an article on the NSK page about JPX where they explained they had been the soured for the bearings of jpx turbines since the beginning. But they say the measures are 10x26. Maybe someone can tell me the ref of the original bearings so I can call NSK.

Therefore, which are the correct measures for the bearings???

I have called JPX and they no longer give support for the engines, nor they have bearings or other stuff.

I am sure there must be someone out there who has fitted standard bearings, and must know how to reassemble the unit. If using standard bearings, I suppose I need to rework the shaft??

There is no greatness on being an expert on something, if one takes that knowledge to the tomb (this is aplicable to all fields in live). I am sure there must be someone around the world who has done all this before and could make a good description that would help others, and remain for the future.

Any help???

Regards, paco

[email protected]
[email protected]

pacomb

I forggot the link to the NSK article:
http://www.eu.nsk.com/FRA/news/2674.asp

paco

Helijack

If you have the old bearings the part number should be on it. They are pretty standard across the world. Should be 4 numbers or so.
HTH
J

S_Ellzey

I have a 260 with bad bearings. The original bearing where made by SNFA in France. Don't bother asking them, they will deny that you have a set of the bearings. SNFA claims that those bearings where for military use only, and that no one else could have any. Best I can figure some one at JPX had a back door into SNFA and managed to get the bearings.

I think that NSK makes a bearing that is close, but the ID is slighty large. The best idea that I heard came from an engineer who designs military jet engines. He suggested that the shaft could be crome plated and carefully ground to match the bearing that you can get. This would have to be done by a high quality machine shop. Your only other hope is to find some one who still has a set of SNFA bearings.

WrenTurbines

We had a JPX here some time ago, belonging to a customer who asked for advice. The guys looked at it and said it should be possible to use standard GRW cageless turbine bearings if the shaft is ground minutely smaller, down to a standard metric size. You would also need to make a new spacer.

We didn't have time to do the work but the guy seemed quite happy and said he'd take it to a machine shop. I don't know what happened after that - sorry.

Sara Parish
Wren Turbines

digitech

My Feedback: (10)

he now uses as a paperweight and got a Wren?

kidding aside i sold about 80 kilos of jpx stuff a few months ago.
i could remember that the bearings where a bit special.
have a look on german forums and ask around i am sure there are still plenty out there
also mail a guy called Thomas Baumgart (turbinenmuseum.de)
he is a good friend and still knows alot about these things.

Nick C

yep , I went through exactly the same thing a couple of years ago. I measured my shaft as 10.16 as you say , and the ID of my bearings is 10.2, but they are all knackered. I did speak to somebody at JPX and they were all keen when I spoke to them but nothng ever happened. Thing seems to be to get the shaft ground down to Ø10 mm or slightly under that, and then you can use standard ISO 6000 bearings.

Mach1

My Feedback: (5)

You might want to contact these folks...

They carry SNFA bearings and have the following on their website:

Obsolete bearings
If you are having trouble tracing obsolete bearings, bearings which are no longer supported or manufactured, then call us. Between our staff members we have many years of combined experience over a vast range of bearing manufacturers. We hold interchange and catalogue data dating back to before World War II, and our ability to trace a bearings heritage is unmatched. In some cases, bearing manufacturers have approached AHR for help on certain bearing identification issues. All we ask is that you remember us when it comes to ordering your bearing requirements.


See web site:
http://www.ahrinternational.com/obsolete_bearings.htm

Contact info: email
[email protected]

phillfix

Hi guys
Yes the bearings for all JPX where special make and arn't manufactured any more anywhere.
I've been fixing them for some time (since run out of parts).

There is two ways you can go (1)you can get the rotor shaft ground down to 10mm to take a standard bearing (boca) remember that the spacers and compressor wheel have an ID of 10.1mm nominal and require a bushing or a new component made .

(2)Buy a set of (boca) bearings, disassemble them and have an engineering shop open up the ID of the inner race section on a tool and cutter grinder to fit your shaft.
I prefer the second method as thats what I 've used in the past.

rcdriver22

My Feedback: (1)

How do you re assemble inner race and outer plus all the ceramic balls?? [:-][:-]

Do you remember those hand held games when you had to land five balls into five holes now add another 10 extra balls[&:][&:]

Paul

hmjets

very easy,warm the outer ring with a small torch, then put the ceramic balls with grease(silicone,vaseline,etc) to retain the balls in place.I hope this help![sm=thumbup.gif]

DThomson

I have a good workign JPX 250 if you need it. Please send an email to [email protected]. I will make it very affordable for you since I am not using the engine. It has only been run 3 times.

David

pacomb

Hello all, for all those interested in the JPX turbine engines, I have been able to get the original video tape VHS made by tramplet. I will make it digital.

My shaft is being regrinded by a specialist. Will let you know. Also he is making a new spacer.

There is also one thing that makes me wonder. There is a metal gold part, as far as I know if a ceramic bush with an internal spring, that fits in front of the front bearing, and at the rear of the compressor. This part looks to have the internal material craked. What is this for??? how can over come it???

Regards to all

Paco

Pegasus

The 240 used a stock turbo charger part for a air seal to seal the compressor section from the rest of the engine. If this piece is cracked I would not use it, it is made of carbon, you don't want parts of it coming out and going through the turbine. JPX later left this part out and replaced it with a spacer and a none touch type air seal. I have done this conversion on a 240 and it worked fine. I will try to fine a picture of what this part looks like.

rcdriver22

My Feedback: (1)

Thanks hmjets

I tried this after Allan at abcmicroturbines.com the guy who sells the parts to upgrade your KJ66 from 18lbs thrust to 29-30lb thrust[8D][8D] Excellent online trader and GTBA member, confirmed how easy this was!

Firstly the heat is not necessary and just discolors the rings. Grease, marg (not sure of US name) or baby's vasalene is great. Stick the ceramic balls to the outer race (there is more space here and especially on a MW54 bearing there are 14 small balls)

On a hard board press the inner race home 'voici la solution' In thinners or jet A1 wash out thoroughly. lighly oil and spin until up till nearly dry avoiding drag on or skidding of the balls in heavy oil. "quÃ* está la solución"[8D][8D]

Thanks to those here on these jet threads and on the Gas Turbine Builders site (now ONLY paypal subs with years of great reading. Great[8D]

Paul
RCdriver

Provider of the FREE issue of Jet Power Int mag in English.
http://www.rcuniverse.com/forum/m_32...agazine/tm.htm

gregmax

Paul,

Does Allan still produce the upgrade kit for the KJ66 as I have a KJ sitting at home that could do with it?

Have you done the upgrade (or had the upgrade done for you) and how did it turn out, is it a worthwile upgrade?

How much did it cost?

Thanks

Greg

rcdriver22

My Feedback: (1)

Greg

Allan was poorly last year but in the back in the harness. The upgrade is not cheap at about £1100. The results are impressive! I nearly flew my workmate down the garden![8D] I'm getting a gold Mw 44 so if you want to do a deal my has 35 minutes from rebuild so just about new, I'm your man. This week upon GTBA advice I finished it and sprayed it with manifold high temp paint and it looks rather good. We might do a trade and I'd be happy if you took it to try on a 10 day sale or return basis, I know you'll be impressed as are many others.

Paul

gregmax

Paul

£1100 is a lot more than I was thinking/hoping it might be.

I think I will wait for the XL200 and see what that will be like!

Thanks for the offer. Enjoy the 44.

Greg

SJN

I used GRW bearings in my JJ and I think my simjet has them too.

http://www.grw.de/english/default.htm

http://www.grw.de/english/modellbau.htm

http://www.grw.de/english/frame.htm

rcdriver22

My Feedback: (1)

Greg

I have misled you, the full KJ 66 kit is £1100, the upgrade price is on application to Allan.

"Available now a range of new parts that will increase the power in your KJ66 type engine from 18lbs of thrust to around 30lbs , the parts consist of a modified diffuser ,a different tunnel assembly and a 70mm compressor wheel , complete front end inc bellmouth and combustion chamber you still use existing fuel manifold , NGV and turbine wheel, parts are available as a kit or you can buy them individually.In order to use our front end you must use a full length CV470 gas cylinder for the engine case , or make your own engine case to suit our range of parts.

Upgrade Kit P.O.A."

drop him an email tonight at [email protected]

Cheers Paul

Pegasus

pacomb,
Here's a pic of the air seal they were using in the later motors, if you have access to a lathe you could easily make one of these and a stainless spacer the width of the seal that came with your motor. You will need a .015" clearance between the two pieces.
I hope this helps.

Kelly W

My Feedback: (2)

Kinda funny to see a Canadian penny all the way down in California!

Sorry to skew the thread... Ewald, If you've got any more photos of this particular turbine's guts I'd like to see them out of curiosity...

Kelly

Pegasus

It figures a Canadian would pick up on that. LOL What other pictures would you like to see?

Kelly W

My Feedback: (2)

Pretty well anything you've got handy. I met someone last year that had one of these given to him and it seized up. (I'm pretty sure it was a 240...) I had no idea if I could help him or not due to the lack of exposure I had with them. I only really know KJ's an onward.

Kelly

Pegasus

I have a shot of my Titanium version all apart, I will see if I can find it and post it here.