Knock in ST5

[Ian]

Doug - Yet even more good stuff. Many thanks.

Regards,
Ian

[lendusaquid]

Ill get me new bearings and try the fit in the housing.If they go in with a light tapping with a rubber mallet then i will be happy. Your info on the centering of the rotor in the core is a bit of enlightenment for me. Ill adjust the alignment aiming for that. Alot of what your saying about fitting bearings is somewhat scary, is this another fuck up i see before me . I was going to hammer the new bearing on with a piece of pipe and never thought about the rotor shifting on the shaft. Would putting a bearing on the ground and pointing a propane torch into the hole  for a few seconds be safe to heat it ?

Using Windoze on a computer is a bad idea, i use Debian sid.

Never thought using your real name on the internet was a good idea.

Graham 

[lendusaquid]

xyzer
Its a Poly V belt, L profile, and i probably havent got it set up as good as i thought.

Ian
Yes i still think its moving axially.There is very little slop in the bearing although i think its a bit rough.I changed the grease only a few months ago and now its black, o no my bearing housing!!

Rab
Got the GDSF coming up soon, see if i can find an old som head ,you never know.

 

[oliver90owner]

GDSF  You had better get there early!!!

Regards, RAB

[Doug]

Guys never put a flame on bearing you intend to use Period!

If you don't mess up the heat treating with a torch you will burn up the grease.

Here's what you do set it in the oven for 15 minuts at 250 F. NO HOTTER!

Move fast that bearing will cool quick and it will cool even quicker on the shaft.
Onther way to go if you can get your hands on dry ice is to cool shaft and slide on abearing you warmed in the oven. This was is easier because your not scalding your hands with a rag of fumbling with gloves on.

There is the possibility you going to have to tap that bearing so making a tool that is only going to aply force to the inner race of the bearing like a pipe is a good I idea and have it handy just incase thatbearing is stuck half way as the temperature of the two metals ( shaft and bearing ) come together.

Last Summer my ST-5 not much help here but here is proof I screw up. That bearing was not hot enough and the hot plate didn't heat it evenly I had to use the impliments of destruction and drive it home.

http://www.putfile.com/dougwp/media

http://www.putfile.com/album/102508

I bought some cheap cold chisles and gound the end flat and slight spoond it for bigger bearings. Your not going to need a lot of force to keep a cooling bearing moving if it stiffens up as you lide it on, but I don't recomend this unless your very sure of yourself nand have steady hands ( stick with the pipe ).

Don't go malleting away at a bearing even with a rubber one to get it in that housing Graham. Odds are you will drive it in at a slight angle and not be able to remove it. This is just a hand fitting and odds are if you have a good tight fit you may not be able to get that bearing in at all. If it turns out to be fairly easy to slip that bearing in and it moves easily and freely I would be a little suspect. Small bearings like this have a machined fit of in some cases only .001 to .002 of an inch ( but don't quote me I'm pulling numbers out of the air ). And this is cast iron with pours and machining marks so it may offer some reistance to sliding just becasues of that ( wipe with steel wool or some 600 grit paper if realy roungh but never any more than that just to rumove bumps or rust )

I might make this sound scary but its not, its just a different skill and " fitting " as we called it in the trade takes a little getting used too. This is no place for a 16 year old who's favourite tool is a hammer ( and every probelm looks like a nail ).

At some point someone is going to screw something up and blame me so guys if your not comfortable doing this or things give you real trouble piece of mind is only as far away as the nearest rewind shop ( have them strip replace bearing and even spray some Glypotal 1201A ). This will cost you a bit of money but you know its done right. If they have the machine you could also ask them to check the brush rigging and fix if needed and take a cut off your slip rings if they are rough or badly machined and lastly they coudl also stone and seat your brushes for you.
All this costs so get a quote but thats why its called a trade.....

Doug
We've been through all this before in other threads fitting stoning, brusgh rigging and even the Glyptal 1201A electrical sealer for the windings

[lendusaquid]

Bought my new bearing today,made in japan,NTN,never heard of them.$48. 6309zzc3/2as. There was evidence of wear in the housing but the new bearing is a tight push fit thank god. I asked the man in the bearing shop whether the bearing should slip slightly over time in the housing and he said no, if it slips it will wear the housing. It was his business and he has  been in it for 30 years. O dear now i have to make a decision.I think some reading is required.

[Doug]

He's wrong a bearing will move a little the outer race will with time ever so slowly turn. It has too that is the nature of things that move one is lightly smaller than the other and one will slowly move.

Now I was always told they don't move and if they do they wear things out. Over the years I noticed things did move and I tried to stop them. Another member on this site enlightend me and said this is normal and natural and is better for the bearing because all the moving parts inside will over time move and wear together and this makes a lot of sence to me now in hind site. If a bearing make a rotation in that housing every 50 - 100 hours or so I would not worry and consider this normal and as long as it doesn't speed up and start to actualy spin and wear thats ok with me.
 If a bearing is too tight the compression on the outer race distorts the bearings inner parts and causes faster than normal wear so. If the housing is oblong then it distorts thinsg and causes excessive wear.

48 dollars for a pair of 6309?
Thats sounds higher than I expected by about 25% but I guess that include VAT and shite like that right?
NTN makes a good bearing.

You have much heavier bearings in your than I do in mine.

I would feel more comfortable if you took my advice and had the housings checked now, its apart and that box of doughnuts and tray of coffee will probaly get you a free look see from the machine shop if you are friendly and patient.
Peace of mind is very cheap at the cost of doughnuts....

Doug

[lendusaquid]

I dont think there is any problem with the housing.It was a nice tight fit with the new bearing and as such i will not be loctite`ing it into place.But i will be keeping a close eye on it. I can see the logic in what you are saying about bearing wear and will go with it. If things start to slacken then i will loctite it in giving plenty of room for expansion at the other end of the shaft. Yes it is alot of money for the bearing and it was cash no receipt.  And ive seen them online for half that amount. Infact ive just bought a cheap and nasty one 5 minutes ago online for $10 incase of emergency's.
Looking at your hotplate i was thinking that my exhaust silencer is big, and if i could keep it in place without falling off it would heat the bearing a treat.
I have a wavy washer in the fan end, would adding a wavy washer in the other end be a good idea?

There are some metal spinners a few hundred yards away from me so i could drop in and see what they think of the housing. Ill do it to keep you happy. If i suck the jam out of the doughnuts  i could tell them that there low fat.

[Doug]

Graham the hot plate it was a bad idea, and I couldn't heat my bearings properly. If I can't reliably heat and judge the heat this way you probably will not be able too yourself

Preheat the wife's ovent ot 250 and warm the bearings that way

Bring the rotor in thouse, put it on the kitchen table and gett some good cotton gloves to protect your hands ( odds are rags will just make you fumble )

For added insurance get a couple of cans of key board duster, invert the can and spray the liquid on the shaft. this will freeze the shaft downbellow 0 and buy you a little more room and time.

Lastly make sure if there are shims behind that bearing ( and sometines the factory will add a shim or two but not saying its there ) it stays there.
Have your hammer and pipe readyand when you think the bearing is whereit should be give it a light tap tap make sure. The whole rotor wil give a nice solid ring when the bearing is in place and you tap it and a thud and some forward bearing movement if its not.

Last thought and comment:
Some people fill the void inside the end bell with some #2 bearing grease about 1/3 to 1/2. This is not a bad idea since the grease will in time bleed a little oil into the bearings. You have 2ZZ bearings or shielded type, these arenot sealed and will pump a little grease from that 1/3 filled resevior if they need it in the course of a year or two ( afetr that point the grese is bled out and not much use any more ). You may want to do this ( grease also acts as a dust dirt trap and prevents rust in the end bell void around the bearing.

I used a product call ed Esso Gearteck open gear lube. Its noa lubricant in this case for me but just a thick gummy coating that will allow the bearing to move in its housing and prevent rust. You can't buy it, its actualy used as wire rope dressing and for lubricating open gears. 

[lendusaquid]

Yet again a lot of very interesting and useful  information from you Doug, thank you.

Graham

[lendusaquid]

Found this. It also backs up what you have said Doug.

http://www.ntn-europe.com/de/en/documentation/ballRollerBearings/technicalData/pdf/allPages.pdf

[lendusaquid]

I was wrong about the bearing being a tight fit in the housing. Had the housing on the bench while playing with the new bearing and it just slid straight in. Looks like it will have to be loctite.I will remove the wavy washer,loctite the bearing in leaving the other end to float.

[mobile_bob]

lendusaquid:

unless that brg is very sloppy, forget the loctite!

as the brg warms up , which it will under load the outer race will expand and the fit will become plenty tight enough.

remember a good portion of the heat built up in the rotor will end up in the shaft and be transferred to the brgs and then through
to the case end bells.

i really don't think you have an issue myself.

if the brg will slide in and stay put when you invert the housing (just snug enough to hold the brg in under its own weight)
then it is good enough to go in my opinion.

you might use a blow dryer and heat the brg up to around 200F and my bet is it will be a bit tighter than a slip fit.

that brg will run alot longer if allowed to creep and rotate in the case a bit than it ever will being locked in place.
but depending on your application, will dictate which approach is appropriate.

if you are only going to use the genset for intermittent standby use, then loctite it in, the brg will likely outlast you anyway.
if on the otherhand you plan on running long hours of steady use, then i would not loctite it.

but that is me, what do i know?



bob g

[Doug]

Do you think the temperature differential between the bearing and housing makes that much difference Bob?.

Cast iron and steel have about the same expansion rate do they not?
So how much warmer do you think the two might be and how much would you need to take up say .001?

Great point you bring up Bob.

Another thing about Loctite, it does fail and bit of hardened goo will often mix with churning grease that can get pumped into the bearing. Even if the loctite holds I have seen what I think is evidence of loctite ( excessive ) causing the problems with contamination. St heads dont; have grease niples or purge ports so anything ( dirt included ) that gets into that grease reseviour in the end bell risks getting pulled into the bearing ( if its not a sealed type ).

Probably should only consider loctiting a 2RS then ( again more stuff I never realy thought about untill now ). 

[mobile_bob]

Doug:

yes the steel brg and the cast housing have about the same expansion rate, but
the brg will be the hotter of the two and will dissipate its heat into the cast end housings

being the hotter part it will expand more than the housing until there reaches an equalibrium
wherein the end housing is drawing off enough heat to keep the brg cooled and from expanding further.

a good portion of the rotor coil heat finds its way down into the shaft and through the brgs, as well as the frictional
heating within the brgs, even the lube will heat up when the brg is spinning.

i think a thouands of an inch is not much under load, and probably goes away as the brg warms up

thats only 1/2 thou all the way around

bob g