Gallery, Projects and General > Project Logs
Modified Rocking Engine
NickG:
Thanks for the replies guys! Feeling a bit more up beat this morning, there are 12 components left, but some aren't as fiddley as that one, so if I get my finger out, I could do it in a week I think! Beware though, i've made these sorts of bold claims in the past and a month later I'm still applying finishing touches!
Chris,
With regards to Alibre, the way 3-D CAD systems work is that you create all of the geometry from 3D building blocks as it were stuck together to form 1 part. From that, the computer can generate / project the 2D geometry by just looking at it from different view points. That's all you do when you create the 2D drawing. It asks what views you want and you just place them on a sheet of paper. If you have your preferences set right it'll automatically dimension it for you, however, I'm not a fan of that, it sometimes jumbles them up and doesn't necessarily put the dimensions on that you or I would knowing we have to make it next! Then you can do other things like sectioned views and detailed views where you blow a small feature of a part up to a larger scale for clarity. Once you have the 3D model and 2D drawing they're linked. If you update the model and save it, the drawing automatically updates. Similarly, with the assembly, which is a file with all the parts mated together, this will update if you update any individual part.
With the assembly you can mate parts with the correct constraints they would have in real life, therefore giving it the degrees of freedom it would have in real life which means you can grab the flywheel and spin it over! Unfortunately this version of Alibre doesn't have the animation add on which is an extra so you can't get it to do it automatically. Keep going with it, you'll love it. It takes a bit of practice, I've used various 3D CAD systems for years and they all work in a similar way, think that's why I picked Alibre up so quickly, have to say it's the most intuitive one of the lot.
With regards to your comment about tooling, that is spot on, that's exactly what happened to me last night!
Keep watching and I will post regular updates!
Cheers,
Nick
NickG:
Hi all,
got a little bit more done but am afraid this thing is going to take longer than I thought, probably 2 or 3 weeks!
After doing that little pedestal I couldn't face doing another 2 yet ... bored of that! (No patience!) So, I decied to do the cylinder and cover. I'd been mulling it over in my head overnight and thought that if I get the cylinder done except the bolt holes, then the cyl cover finished, I could transfer the holes from that into both ends of the cylinder and the frame when that's done. Then everything will definitely line up.
Unfortunately after 3 hours in the workshop I cam out with no finished components! :doh:
I've got the cylinder and cover part done, just need holes drilling in cover, transferring to cylinder then those tapping 8ba.
I made a bit of a mistake on the cylinder which is annoying as there couldn't really be a simpler component! I didn't bore it out quite long enough ... thought I had allowed a good 1/8" extra when I drilled it, but I must have stopped boring short of the drilled hole. This was probably due to boring a blind hole ... at least I can learn a lesson from this, bore it right through. Anyway, this has resulted in the cylinder being 1/16" shorter than it should be. So I'll need to change the drawings, I'll need to make the crank throw shorter and move the bearing hole further away! :bang: I was going to use an adjustable reamer I'd found to finish the bore, but I found the surface finish from boring good enough. Just as well because for the adjustable reamer I'd need to have bored right through anyway. I found a nice piece of phosphor bronze for the cylinder.
I originally called for steel for the cyl. cover, but saw a bit of that nice aluminium so used that instead. Pretty simple turning job. I always used to find it difficult turning little registers for a good fit in the bore but on this lathe I seem to be able to get it spot on. The sali machines really well and I parted it off with on the slowest none back gear speed and the slowest cross feed. Worked superbly. Had to put back in the chuck to finish the outside so put a bit of aluminium from some old vanishen blinds around it to protect it from chuck jaws, nipped the jaws and used the tailstock chuck to push it to run truew whilst rotating at slow speed.
Apart from the silly mistakes i keep making it's going quite well. Still frustrated by how long it takes to change lathe tooling etc though. What I am happy with is the surface finish I'm getting. If I keep this up, I prob won't be trying to bling anything, just a quick polish with a rag and some silvo to keep the dirt away, or eve just with oil and abit of wire wool. I really need to get a polishing attachment for the grinder if I want to bling stuff.
Anyway, here are the part finished parts! Look a lot better in real life, camera never does stuff justice!
Nick
Brass_Machine:
It is a neat thing to see an engine (or whatever) go from design to build!
Way to go Nick!
Eric
NickG:
This is going slowly! I need :poke: :poke:
All I got done today was finish the cylinder and cover.
I put the cover in the lathe and made it run true the same way as I did before, brought the tailstock up to it whilst nipped in chuck and running slowly.
I marked the positions of the 6 holes by lightly scoring a circle of the right dia. with the cutting tool on the inside face, then indexed using the 3 jaws of the chuck and a small spirit level on each jaw getting them as near as I could to horizontal each time and scoring across the circle with the cutting tool.
Centre drilled and drilled through, it's tough stuff this aluminium though, made me realise both my no 50 drills were blunt so had to go through with 52 first.
I then put the cover on the cylinder and spotted through the holes on both ends. The 6 divisions are good enough not to be able to notice by eye but they won't line up in any position, only 1! I need a rotary table with compatibility to lathe chuck but this will do the job, so long as I spot the frame holes with the cover too.
I opened up the holes to 8 BA tapping size in the cylinder and started tapping the holes. Used a taper tap in the drilling machine to get them square then thought i'd just do it by hand with the plug tap so I could get more feel.
All was going well and I was just thinking to myself, I used to break taps like this .. I was so careless back in those days, am much better now. 10 mins later this thought came back and bit me in the @rse and the tap snapped! :doh: :bang: Think my taps were pretty blunt. Without thinking I tried to get it out using a centre punch, which didn't work, just made a few scratches on the end face of the cylinder and a bit that pinged off hit me in the cheek. Could have been nasty if it were a bit higher, I wouldn't care, I'd had my glasses on 90% of the time too. Always wear safety glasses.
After conceeding I wouldn't get it out I thought well, I don't really need to. Luckily it was in the end that bolts to the frame, so all I'll have to do is tap that hole in the frame and put a dummy bolt in instead of drilling clearance size. 5 bolts are more than enough to hold it.
Here are a couple of pics. First of the frame end with the broken tap. :bang: :( :wack:
No one will be able to tell once it's together. Hopefully no more mistkaes!
On another safety note, does anybody wear gloves whilst they're in the shop? I know there are other hazards associated with gloves and machinery but I'm for ever getting little shards of metal stuck in my hands which can be painful and difficult to get out. How do people avoid this ...guess never touching swarf with bare hands would be a good start but I can't seem to avoid it.
Nick
raynerd:
Looks good to me !! :thumbup: :thumbup:
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version