PeeWee V4 slow build

[Cogsy]

I feel your pain Michael, I guess the only bright side is that you're not quite ready to build yours yet, so hopefully getting the castings replaced won't hold you up.

I sure hope the foundry issues have been sorted out now.

 

[michael-au]

I have sent some pics to Dirk, I hope he will replace them

 

[Cogsy]

As it will be a while at least before I get more castings, I decided to have a go at the crankshaft. This will be my first one piece crank, my first multi-cylinder crank and also my first attempt at offset turning.

I could be going about it all wrong but here's what I've got so far.

A nice lump of 1" 1144 stressproof cut to length and faced, along with a set of (most) dimensions.



I started by squaring the blank to the mill and machining a flat 1/4" deep on one end. My first impression of the 1144 is that it machines beautifully. I have some 12L14 to machine later on, I hope it machines as nice as this stuff.




Then I flipped it over and used this setup to indicate level on the cut edge, then machined another 1/4" deep flat.




I didn't take any photos of the next couple of steps, but I used the machined flats and centre drilled 3 holes for crank and throws offset. Then using the flats again I indicated the other end and centre drilled the matching 3 holes.


As I've never turned between centres, I machined up a drive out of some mystery steel - it's not pretty but it is machinable.

 

[Cogsy]

Here's my complete set-up being tested between centres. First on the centreline.



And then one of the offsets.



It all seems to be working as planned so far. I don't know what sort of RPM to spin it at, but at the moment I've tried it at around 500 RPM and it doesn't seem fussed about the imbalance.

As I now intend to do all of the work on the lathe (no roughing on the mill) I thought a couple of carriage stops for the lathe would be helpful. So without any sort of plan or research I whipped these pair up. They work well and should do the trick nicely.

Now I need to grind up my parting blade, make sure my gibs are adjusted and start making chips on the crank. I may start tomorrow but the wife may have other ideas. Any good advice would be appreciated (about the crank, not the wife).

 

[michael-au]

Take you time and measure twice before cutting ( advice I should have followed ) and you will be ok
When you have one of the offsets turned bolt a block in the gap so it does not flex when turning the next offset, when that one is machined bolt a block in the gap, so when you turn the ends it won't flex and should stay straight

 

[gus]

Hi Cogsy.

Will be watching the crank shaft cutting. Soon or later will get enough Dutch courage to cut same.

 

[stevehuckss396]

Any good advice would be appreciated (about the crank, not the wife).

Rough it out in the mill first. It will save a lot of time and increase your chances for a good result. It will also be easier on the tooling in the lathe.

 

[Cogsy]

The crankshaft is done - when I say done, I mean destroyed, in the garbage. It was going well and I thought I'd thought of everything, but I forgot to allow for sheer stupidity and it snuck up and bit me. I managed to miscalculate my roughing cuts and missed my dimension on the first throw :wall:.

So how annoyed was I? I said a bad word (just one), then I thought some more bad words (lots), then I had a bit of a think about it and I made my peace. Even though I had quite a few hours in it, I wasn't overly confident I'd be able to pull it off. Now I have a test piece that I can finish machining with no worries about making a mistake. At the end of it I'll have an interesting paperweight and hopefully the skill to make a successful crankshaft.

I'll make a start early next week. It's forecast to hit nearly 40 degrees celsius here by next Friday and I'd like to be done by then. With nothing but a small fan my shed is uninhabitable one the mercury hits 36C.

 

[Swifty]

That's a bummer Cogsy, but put it behind you and get on with another, it will soon be forgotten.

Paul.

 

[michael-au]

That's a shame....best you can do is look at it as a learning curve.
Hope the next one goes well

 

[e.picler]

Al
If the problem is on the diameter of the throw you still have a chance to use the crank, just make a special connecting rods for that specific throw.

Good luck on the next.


Edi

 

[Cogsy]

Thanks for the thoughts everyone. A stupid mistake is what it was - just forgetting from one moment to the next what number I was aiming for and hitting the wrong one.

Edi - I have made a commitment to myself with this engine that close enough will not be near enough. If I make a mistake on a part I will remake the part. It's not the way i normally operate (we have a saying here in Oz - "she'll be right mate") but I'm making the attempt to get some better habits happening.

Really, we are in this hobby for the fun of making parts, otherwise we'd buy the pre-machined kits, so I look at it as being some extra 'fun' in the build. Really though, that 'fun' was hours of gritted teeth and 'pucker' while I hoped nothing would go wrong...

 

[Cogsy]

Here is the prettiest piece of scrap I have ever made.



I learned a lot about the cutter I need to use and the machining steps, etc, but I'm still concerned I don't have enough skill to make a usable crank.

Somehow, even with my spiffy drive thingy, I still managed to have the crank slightly off centre from one set-up to the next. I'm not sure how this is possible - I didn't remove the drive from the chuck at all during the whole machining and never moved the tailstock either. All I can think of is there may have been a little bit of swarf in the centre holes at some point and I didn't notice.

I machined the centre bearing journal, then the tailstock end shaft and finally the shaft closest to the chuck last, all without removing the crank from the lathe, so all 3 sections should have been concentric. The first two went OK but on the final shaft I was having trouble with taper, then I noticed run-out on the other 2 sections. I assume I got some shaft flex while I was turning the final shaft. I measured the run-out at a maximum of 10 thou on the centre journal. Far too much. I'm not sure why this happened, except maybe I let my cutter get a little bit blunt and had to apply more cutting force. I guess I won't know until I try the next one.

Well it was fun, now lets see if I can improve on it.

 

[MCRIPPPer]

even if you didnt remove the drive dog from the chuck, you could still get runout if the center spike is not perfectly centered, and you flipped the crank 180. could also be the bolt you have for clamping onto the crank. you could probably do without the bolt and just let the crank float.

 

[gus]

Hi Cogsy,
Been following the crankshaft machining. Will continiue with the next. No worries.

 

[Cogsy]

Since all the holiday duties are over and I have a bit of free time again, I thought I'd start on the next crankshaft. As I knew it was going to get hot here today (the forecast was 39C), I got a reasonably early start and managed to get some work done.

But, after a couple of hours I noticed my head getting a bit 'fuzzy' and I had to keep checking everything I was doing, so I figured I'd had enough. Then walking to the radio to shut if off I had a little stumble for no apparent reason. Weird, I thought. I was feeling a little queasy and wondered if I was coming down with something. Then I checked my trusty thermometer which advised me the air temp in the shed was a balmy 47 degrees celsius . And I hadn't had a drink in at least 2 hours . Into the cool house and a couple of litres of water later and I felt a lot better.

I've never had proper heatstroke but it was surprising how easy it can creep up on you. I'm guessing another half hour in the shed and I might have been in some real trouble.

Tomorrow is forecast for 41 C so I think I'll get some inside jobs done instead.

The crank is looking good so far though. Fingers crossed.

 

[gus]

Since all the holiday duties are over and I have a bit of free time again, I thought I'd start on the next crankshaft. As I knew it was going to get hot here today (the forecast was 39C), I got a reasonably early start and managed to get some work done.

But, after a couple of hours I noticed my head getting a bit 'fuzzy' and I had to keep checking everything I was doing, so I figured I'd had enough. Then walking to the radio to shut if off I had a little stumble for no apparent reason. Weird, I thought. I was feeling a little queasy and wondered if I was coming down with something. Then I checked my trusty thermometer which advised me the air temp in the shed was a balmy 47 degrees celsius . And I hadn't had a drink in at least 2 hours . Into the cool house and a couple of litres of water later and I felt a lot better.

I've never had proper heatstroke but it was surprising how easy it can creep up on you. I'm guessing another half hour in the shed and I might have been in some real trouble.

Tomorrow is forecast for 41 C so I think I'll get some inside jobs done instead.

The crank is looking good so far though. Fingers crossed.

Hi Cogsy,

Take care.

Gus could not handle 36----38 C while on Biz Trip in China. Was sweating away losing too much salt.

 

[Cogsy]

Gus - I struggle with heat as well, but high humidity is worse for me. I spent a month in Darwin once and I almost couldn't drink enough to keep up with the sweat I was loosing. I'm guessing Singapore is probably worse.

BTW - it's 10:30 in the morning here right now and already 38.2 degrees. Looks like it'll be warmer than the 41 they predicted.

 

[///]

Jeepers Al!!!
Glad you're ok.

I experienced similar many many years ago when I passed out in the shed. Was a typical Perth summer day, stood up to exit the shed and I got tunnel vision followed by complete white-out. I made it to the doorway and clutched on hard with both hands waiting for my vision to return.
Next thing I can remember is waking up on the concrete floor with a very sore bump on the back of my head and a ringing in my ears. I have no idea how long I had laid there, I was home alone at the time. Scary stuff.

I think you are right about today's temp, feels over 40 already outside.
I'm in a nice air conditioned office but miles away from my shop

EDIT: You were on the money Al, 42.9 in the city at 12:25pm. (~110 Fahrenheit for you US viewers)
Temps typically peak around 2 to 3pm, so could go higher!

 

[Cogsy]

We ended up hitting 44 degrees here today (115F). Needless to say I didn't get any shed work done. There's a cooler change expected about the end of the week so with luck I'll get the crank finished then.