That's pretty much what I did, except that 1) no CNC, so I used the rotary table, and 2) I went ahead and made the holes full-sized, and made pins to suit for the tooling plate. Your approach will be quicker and easier!
Yet Another Webster Begins
- Thread starter CFLBob
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That's pretty much what I did, except that 1) no CNC, so I used the rotary table, and 2) I went ahead and made the holes full-sized, and made pins to suit for the tooling plate. Your approach will be quicker and easier!
A Traxxas 4033 carburetor will run this engine just fine. So will chuck's carburetor.
Thanks, Brian.
That Traxxas carb seems like a good trade off of a little cost vs time.
That Traxxas carb seems like a good trade off of a little cost vs time.
I have the rod roughed out and ran into a problem with cutting the final pass, which takes off the 1/32" in the middle of the rod and leaves the circular outline around the bearings. I'll do that same cut on both sides of the rod.
I'm using an old version of DeskProto for my CAM program and it just refuses to do things the way I think they should be done. I see this as cutting an arc on each end of the rod, but I could do two circles instead of arcs and cut a lot of air. It's an easy piece of Gcode with the G02 or G03 commands. So I wrote a file to do it that way. Go to the right side of the first circle I'm going to cut, cut it, the move to the left side of the bigger circle and cut that one. As the cutter moves from the first to the second circle, it thins the whole rod by that 1/32. I proofed the cut in GWizard and it comes out just like it should.
The green is the path of the center of the cutter (1/2" End mill). The red arrows I drew in to show how it's supposed to cut.
I take the file out to the mill, and Mach3 shows an entirely different picture. The circle on the right is so big it includes the circle on the left. I did a test air cut and that's what it did. It's like Mach3 and the GWizard editor are speaking entirely different languages. But only on circles because I often use it to proof cuts and this is the first time they've disagreed.
It looks like I have to spend some time with Mach3 and figure out why it's cutting differently. I know I've done circles before and they came out fine. I made the pieces for my Grizzly CNC conversion on my Sherline and cut out a few circles on the motor mounts, all coded by hand this way.
I'm using an old version of DeskProto for my CAM program and it just refuses to do things the way I think they should be done. I see this as cutting an arc on each end of the rod, but I could do two circles instead of arcs and cut a lot of air. It's an easy piece of Gcode with the G02 or G03 commands. So I wrote a file to do it that way. Go to the right side of the first circle I'm going to cut, cut it, the move to the left side of the bigger circle and cut that one. As the cutter moves from the first to the second circle, it thins the whole rod by that 1/32. I proofed the cut in GWizard and it comes out just like it should.
The green is the path of the center of the cutter (1/2" End mill). The red arrows I drew in to show how it's supposed to cut.
I take the file out to the mill, and Mach3 shows an entirely different picture. The circle on the right is so big it includes the circle on the left. I did a test air cut and that's what it did. It's like Mach3 and the GWizard editor are speaking entirely different languages. But only on circles because I often use it to proof cuts and this is the first time they've disagreed.
It looks like I have to spend some time with Mach3 and figure out why it's cutting differently. I know I've done circles before and they came out fine. I made the pieces for my Grizzly CNC conversion on my Sherline and cut out a few circles on the motor mounts, all coded by hand this way.
You can see what the tool path was supposed to look like above. This is what Mach3 thought it was supposed to look like. The little circle is approximately right but the big circle is way too big and cut in the wrong direction.
It turns out that Mach3 had been set to always be in absolute coordinates. In general, I like that way of working, but it was killing me here. Deep in the manual, page 10-30, it says that this can be overridden for G02 and G03 cuts, which is what I was doing. Once I figured out that's why it was acting like the big circle wasn't listening to my commands, it took very little time to finish it. Cut the circle on one side , which also cut the relief between the circles. Flip it upside down and do the other side.
I notice I didn't center the small end in X, only Y, while I did both for the big end. Ah well...
Back when I took my first programming class there were no home PCs and we had to go to terminal rooms on campus to work on our programs. Every computer room I ever walked into had this limerick somewhere on the walls:
I really hate this damned machine
I wish that they would sell it.
It never does do what I want
Only what I tell it.
It was doing what I was telling it to do.
It turns out that Mach3 had been set to always be in absolute coordinates. In general, I like that way of working, but it was killing me here. Deep in the manual, page 10-30, it says that this can be overridden for G02 and G03 cuts, which is what I was doing. Once I figured out that's why it was acting like the big circle wasn't listening to my commands, it took very little time to finish it. Cut the circle on one side , which also cut the relief between the circles. Flip it upside down and do the other side.
I notice I didn't center the small end in X, only Y, while I did both for the big end. Ah well...
Back when I took my first programming class there were no home PCs and we had to go to terminal rooms on campus to work on our programs. Every computer room I ever walked into had this limerick somewhere on the walls:
I really hate this damned machine
I wish that they would sell it.
It never does do what I want
Only what I tell it.
It was doing what I was telling it to do.
Yep, as a former software developer, I can relate to that little poem!
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This week, I cut the bearings that go into the ends of the connecting rods. Unfortunately, I hadn't noticed that I didn't have the 0.281 (9/32) reamer needed for the big bearing so I had to go order one of those and leave the bronze in the lathe chuck while I waited a few days. I haven't LocTited the bearings in place yet, but that won't take long.
Back when I was working on the crankshaft, I decided to adapt an idea from someone (I think it was Brian, but I'm not sure) for an end with better balance. I cut that yesterday. First the Ta Da! shot, still on the tooling plate and not Done done.
The original has a 1/2" diameter raised area where that big washer is. I'm leaning toward not doing a second pass to make that and I'll just use it like this. Why? I think that raised area is for making this out of brass or bronze and silver soldering it to the crankshaft. Since this is aluminum I'll just use red Loctite instead of brazing it on.
On to the real reason I'm here. Does anybody else use a Fogbuster? Mine quit working as I was starting to cut this. I kept going because the air flow was fine and I heard that the air flow cooling the cutter and blowing away chips was often enough. It worked in the sense of keeping the cutter from having chips weld onto it, but the cut was pretty barf-y looking (technical term). It almost looked like the aluminum melted and refroze because the sides were shiny and ripply. I cleaned up the part's edges with a fine file.
It had plenty of pressure and the air is just fine, it just never sprayed liquid. My gut feeling is it probably has some dried out gunk in it and I need to do something to clean it out. I tried to pull the hoses off it yesterday and couldn't. I almost cut them off and then said I'd go look on their website for some hints. I find no maintenance or troubleshooting help there.
So what should I do? Cut the hoses off and soak it? Ram a pile cleaner or wire or something up the nozzle? Any ideas or suggestions would be appreciated.
Back when I was working on the crankshaft, I decided to adapt an idea from someone (I think it was Brian, but I'm not sure) for an end with better balance. I cut that yesterday. First the Ta Da! shot, still on the tooling plate and not Done done.
The original has a 1/2" diameter raised area where that big washer is. I'm leaning toward not doing a second pass to make that and I'll just use it like this. Why? I think that raised area is for making this out of brass or bronze and silver soldering it to the crankshaft. Since this is aluminum I'll just use red Loctite instead of brazing it on.
On to the real reason I'm here. Does anybody else use a Fogbuster? Mine quit working as I was starting to cut this. I kept going because the air flow was fine and I heard that the air flow cooling the cutter and blowing away chips was often enough. It worked in the sense of keeping the cutter from having chips weld onto it, but the cut was pretty barf-y looking (technical term). It almost looked like the aluminum melted and refroze because the sides were shiny and ripply. I cleaned up the part's edges with a fine file.
It had plenty of pressure and the air is just fine, it just never sprayed liquid. My gut feeling is it probably has some dried out gunk in it and I need to do something to clean it out. I tried to pull the hoses off it yesterday and couldn't. I almost cut them off and then said I'd go look on their website for some hints. I find no maintenance or troubleshooting help there.
So what should I do? Cut the hoses off and soak it? Ram a pile cleaner or wire or something up the nozzle? Any ideas or suggestions would be appreciated.
Just a suggestion, while it's blowing air, put your finger over the end, that will create back pressure in the fluid line and clear chips/dust from the needle valve.
I put the wire up the nozzle and never felt anything. I also increased the pressure from the normal 15 psi up to 30 and that never blew anything out. So I cut off the hoses and put some vinegar into the input that gets the coolant, let that soak for 5 minutes. I can shine a flashlight into it and it looks clean - I don't see anything in it. Nothing helps.
Aside from the problems with the fogbuster, I finished the bearings and the rest of sheet 7.
Those bronze bearings are held in with red LocTite.
It's on to sheet 8 although I've got to get my Fogbuster working again.
Those bronze bearings are held in with red LocTite.
It's on to sheet 8 although I've got to get my Fogbuster working again.
And here's the counterweight, with 1/4 and 5/16" pins.
It needs more finishing to be prettied up.
It needs more finishing to be prettied up.
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looking good Bob.
OK, I made a screwup. See the dimension in red? I have some 1/4" stock that I thinned out to 3/16 - .188 instead of .219.
Put in the scrap pile and start over? Or does it matter?
Didn't realize it has been two weeks since I posted something. Had a temp job I had to put some time into. And then fell through.
Put in the scrap pile and start over? Or does it matter?
Didn't realize it has been two weeks since I posted something. Had a temp job I had to put some time into. And then fell through.
3/16" will work okay.
Brian beat me to it - in my opinion it will be fine; just might have to adjust the pin on which it rides and the location for the tappet that acts against the valve.
Thanks. I got started on the replacement anyway, but it's just cut a bit oversized and squared. And it's .219 thick.
My problem was not understanding exactly how it goes together.
My problem was not understanding exactly how it goes together.
Myself I would start over. With a 0.125 hole cross drilled in the part it will get awful thin in that area. The thicker the better. That's just me.
coulsea
Well-Known Member
I would have used the 1/4 the way it was.
This part took longer than it should have because of my "comedy of errors" (where the important word is errors, not comedy). I wasted a couple of pieces of steel before I smacked myself upside the head about not paying enough attention! I put a 4-40 Socket Head Cap Screw in the tapped 4-40 hole on the right just because. Although that does make it look a little wonky.
But now it's done! What's next?
