Another Paddleducks build log

[sbwhart]

R.... But hang on, it spins a bit too freely 

And it kinda wobbles a bit too 

I immediately double checked the drill to make sure, yep it was 5mm. Then I checked the stainless rod with 1st calipers and then my digi micrometer,

My next move is to get some 5mm silver steel, and then check the bearing blocks. I guess I can make up the baseplate in the meantime. Oh well, just goes to show that you can't always trust 5mm stainless to actually BE 5mm.


Tim

Great work Tim you're really getting on with it.
 

There are three main ways to make bar:- Hot rolled or black bar because its hot when they roll it its not highly stressed so won't move when you machine:- Cold rolled/drawn bright bar, they work it cold so you get lots of stresses built up in it: so when you machine and releaf the stresses it may warp:- size wise these methods produces bar thats nominally to size, Ground bar such as silver steel is ground closely to nominated size :- you can get ground mild steel bar  as well.

Have fun

Stew

[CrewCab]

Stew, thanks for that info on bars, I'll file it away for future use  ............. Tim, annoying I know, but immediately your just working on sorting it out, well done 

CC

[spuddevans]

Thanks for that info Stew  and thanks for the support CC 

I was a bit annoyed about the undersize rod, but I'm over it now. These things happen  Could be worse, I could've messed up the main cylinder block


Tim

[Darren]

Ball races sound nice........be a first on this engine I suspect.....

[bogstandard]

Tim,

That rod definitely looks like it is imperial, 3/16" most probably.

One thing I wouldn't suggest for the crank is silver steel. It goes rusty when you just look at the stuff. I always use ground stainless for mine.

This engine will in fact take ball races with no problems, as it utilises a built up crankshaft. But if I was going to do it, I would use needle rollers instead of ball races, unless you can get some very thin walled races. You might also find, one needle roller would do in each bearing block, as if you used races, really they would require one at each end of the block. The choice is yours of course, that was just a suggestion.

Bogs

[spuddevans]

One thing I wouldn't suggest for the crank is silver steel. It goes rusty when you just look at the stuff. I always use ground stainless for mine.

Thanks for the rust warning about silver steel  I didnt know that.

This engine will in fact take ball races with no problems, as it utilises a built up crankshaft. But if I was going to do it, I would use needle rollers instead of ball races, unless you can get some very thin walled races. You might also find, one needle roller would do in each bearing block, as if you used races, really they would require one at each end of the block. The choice is yours of course, that was just a suggestion.

Bogs

I have 6 ball races that might be suitable, they are 5mm inner diameter, 8mm outer diameter and about 2.5mm wide. I kinda thought that it would need a ball race at each end of the block, but I thought maybe it would be ok to go with the 2 races per block on the 2 inner bearing blocks, and then just one on each of the outer blocks (if you know what I mean). I figure that if I only part bore out the outer bearing blocks ( on the face that would not be visable when built up ) and have the face's that are on show just drilled out to, say 5.5mm, then the bearings would not be visable once the engine was assembled, but still doing their job as all the loading is on the inside of the outer bearing blocks.

Does my ramblings make any sense?


Tim

[NickG]

Tim,

I was just writing a reply to the same effect as what you just said. I think it'd be ok with just 1 per block since there are 4 of the. If you just counter bore 1 side of each block so the race has a face to sit against, as you say, just a slight clearance will be fine on the other side and you won't see the ball races once assembled.

Nick

[bogstandard]

Don't forget Tim, you should be using stainless races as well.

I have a lots of my own stainless races of two different sizes that I use in almost most of my models that I design and build, but for other races I want, I have found these to be very good.

http://stores.shop.ebay.co.uk/Dinball_Single-size_W0QQ_fsubZ7867793QQ_sidZ42095710QQ_trksidZp4634Q2ec0Q2em14?_pgn=1

Bogs

[spuddevans]

Don't forget Tim, you should be using stainless races as well.

I just checked and I'm pretty sure they are stainless, they are SMR85ZZ types and I think I'm right in saying the "S" indicates stainless.


Thanks for the link, that looks like a good resource for bearings, quite reasonable too.

Tim

[Stefan Pynappels]

They are stainless, the code is a composite made up of a lot of info:

S = Stainless
MR = Straight rather than Tapered Bearing
85 = Size
No Material Code = 440C Stainless Steel
ZZ = Non removable shield on both sides.

When it comes to bearings the following page might be useful:

http://www.dynaroll.com/system.asp

Stefan.

[spuddevans]

When it comes to bearings the following page might be useful:

http://www.dynaroll.com/system.asp

Stefan.

Thanks Stefan  Good link that. Another one for the growing number of bookmarks. 


Tim

[spuddevans]

I started today working on the bearing blocks. I have decided to go with ball races, here they are nest to the blocks,



With the mill still set up from drilling the bearing blocks I 1st of all drilled through each block with a 5.5mm drill to give clearance, being careful to clean the vice, parallels and vice stop between each operation to make sure the blocks went in the vice in exactly the same position.

Then I mounted a 7.5mm drill, set up a depth stop and drilled both sides of 2 bearing blocks and one side of each of the other 2 bearing blocks. ( when drilling the double sided ones I was careful to deburr each side before re-clamping to drill the other side, drilling seemed to raise a burr that I fear could've thrown off the accuracy )
I then followed up with a 8mm endmill to finish off both the diameter and the depth.



Here they are in the bearing blocks,



This leads me to a (hopefully) minor question, The ball races slip quite nicely into the freshly bored pockets but they are not a press fit, do I need to fix them in some way, maybe a tiny dab of Loctite?


Anyway, I then marked, drilled and tapped the mounting holes on the bearing blocks. Then I turned down the bosses on the bearing blocks. I turned bosses on both sides of the inner bearing blocks, and just the one face ( the one facing inwards ) of each of the outer bearing blocks.



Next up will be the bottom mounting plate.

Tim

[rleete]

This leads me to a (hopefully) minor question, The ball races slip quite nicely into the freshly bored pockets but they are not a press fit, do I need to fix them in some way, maybe a tiny dab of Loctite?

Yes.  If the races spin in the pocket, it will not be running on the bearings.  Then, it will wear on the sides of the pocket.  Not good.

It shouldn't have to be a tight (press) fit, but a drop of loctite won't hurt.  Don't use anything high-strength or semi-permanent.

[Darren]

Very nice indeed..... ...yes use a loctite type product, but maybe wait until you are nearing completion just in case 

[kvom]

On mine the eccentrics touch the outer bearing sides;  I have bosses there too.

[Bernd]

Tim,

I'd wait till you've got the crankshaft in to loctite the bearings. If there loose this will help align them better.

Bernd

[spuddevans]

Thanks Rleete, Darren and Bernd, that's a good point. I'll wait til I've got everything running right before sticking the bearings in place. 

On mine the eccentrics touch the outer bearing sides;  I have bosses there too.

Are the eccentrics on the the very outer faces? I have made bosses on the inner faces of the outer bearing blocks, just not on the outer faces of the outer blocks. ( is it just me or have I just confused myself  )


Tim

[Darren]

I made bosses on all sides on mine, eight bosses....See...nearly got to ten....one day.....

[NickG]

Tim,

you will probably find that when you have the weight of the crankshaft in there the outer race won't spin in its housing as there will be more friction there than there is between the outer and inner race. Nevertheless, I would probably loctite in, or I have heard people just put a couple of centre pops around the inside of the pocket .. but that might be a bodgers way of doing it?!

Nick

[rleete]

Considering it's how the bearing was held in on my truck's A/C, it must be okay.  Harder to remove, should the need arise, though.

[CrewCab]

I have heard people just put a couple of centre pops around the inside of the pocket .. but that might be a bodgers way of doing it?!   

If it works it's not a bodge  ..................... well that's one way of looking at it ............. I'd go with the loctite personally, it's fairly easy to warm up and break the seal if you ever need to take it apart in the future.

CC

[bogstandard]

Tim,

Are the eccentrics on the the very outer faces? I have made bosses on the inner faces of the outer bearing blocks, just not on the outer faces of the outer blocks. ( is it just me or have I just confused myself )

If you fit bearings, you should not have anti friction flanges on the blocks, but on the component parts that are in contact with the bearings, crank discs, eccentrics. They need to be the same diameter as the ball race inner race, and only need to be a couple of thou thick, that is to prevent the component rubbing against both the inner and outer races. Sometimes, the inner race is minutely longer than the outer race for just such a situation, but not always. So you will have to measure them to see if the inner is protruding slightly. If it is, you should be able to get away with not having to cut the friction flanges on the parts.

I hope I haven't confused you even more.

Bogs

[spuddevans]

Tim,
.......
I hope I haven't confused you even more.

No, that has cleared things up nicely, thank you 

I have already cut the flanges on the bearing blocks, but only on the faces that would not normally be seen when all's assembled, so I dont think it will make much difference. I didnt know about making the flange/boss on the other componant faces, but I have made a mental note to do that when making the eccentrics and crank discs. ( assuming that the inner race is not protruding )


Thanks again guys for your help, this place rocks 

Tim

[kvom]

To clarify my earlier post, the right eccentric is outside the bearing, not the left (flywheel side).

[spuddevans]

To clarify my earlier post, the right eccentric is outside the bearing, not the left (flywheel side).

You are right indeed, I've just looked a little closer on the plans and see that as you say the right eccentric is outside of the bearing block. I'll have to turn a boss on that bearing block as I dont have a ball race on the outside of that bearing block.

Thanks Kvom for that 


Tim