2020 POTD Thread Archive

[Flyinfool]

I finally finished building the test stand for my pulse jet engine Filled it with fuel. charged all the batteries, ready to go outside and clamp it to the picnic table for testing, and it started to rain...........They are talking about rain and/or snow most of next week

 

[GoceKU]

Well the digger arrived on a truck without any ramps and no way to get it off, the truck is this in the photo, Tam, no idea is it from the 50's or 90's they are all same. We drove the truck in a steep dich and with the digger he pulled earth to the tailgate and got it unloaded, the guy drove the mini digger back close to a kilometer and i drove back the truck. The truck is as slow to drive as it looks, the mini digger is on rubber tracks and he was only few minutes behind me in a 1 km drive. The deal was the company that will do digging was to bring their concrete saw, but it broke the day before, so i had to scramble and borrow an angle grinder with diamond wheel, and little by little i managed to cut out the square, the digger operator helped, he run the garden hose so i could cut it , that did made a mess but that job got completed. Then i used my hammer drill, drilled couple holes and my big hummer to bust the concrete. The machine had difficulty starting from cold when it was on the truck, i had a test lamp and determined that the glow plugs won't getting power, so i grabbed a piece of fence wire laying on the ground and apply 12v from the battery that was close to the glow plugs and it fired up. We should have stopped then, because we had problem after problem, the caterpillar dealership that "repaired" it did more bad than good. And because of the problems it got dark on us not even knee deep on the beginning of the pit. You can see how tight it is and the digger is misbehaving, it has a mind of his own, we managed to hit the selling few times and the garage door. i'll update you tomorrow.

 

[pontiac428]

Nothing like the sound of a pulse jet in the rain...

 

[Tim9]

Here’s a few more pictures of the shim which was rubbing. And also the bearing after I washed it out repeatedly with mineral spirits , bronze scrub brush, Wd-40 and air. I test fitted it with the spindle and cleaned up the bottom of the headstock.

 

[Tim9]

I had to make new shims and that was a real pain in the butt. The originals are laminated and I’m just not going to spend 50.00 for a laminated 0.063 shim. I soldered some sims and then filed them as best I could get. I put everything together and it’s much, much better. No more slop. But, I will have address the shims again. The headstock isn’t heating up anymore but I’m now using more oil. I have to fix the shims better because I left about 1/16” gap between the shim and spindle . But it’s better. Before, the belt would slip when starting on high speed.
So.... I then decided to look at my little 4-1/2” Cushman 3-jaw chuck.

 

[Tim9]

So I had picked up a real nice old Cushman 3-jaw scroll chuck off of EBay a while back.
But, the jaws were a mess.

Unfortunately, even though the scroll was snug and like new and absolutely no slop at all.... The jaws were buggered up. And, then someone had milled the top of the jaws and and attached steel jaws to the OE jaws in what looks like a modification to have soft jaws. Plus, to make matters worse, I’m guessing the soft jaws were at the end of their usable life because the screws were actually mostly turned down to the point that I barely was able to get a bite with a hex wrench. Thank God for hand hammer style impact drivers. It’s such a inexpensive tool which I’ve used hundreds of times and it almost always comes through for loosening screws or bolts. I did have to heat the jaws because the bolts were loaded with Loctite. And, when they drilled the jaws originally.... it’s not done on center. Each jaw’s hole pattern was a little different so it was a custom fit for each.

 

[Tim9]

What issue was that for those of us that have old cast-iron-bearing headstocks that are wearing out?

BTW, good find. I hope it is a tight as can be when you are done.

joe

Here’s the quote from the Practical Machinist thread in which I stumbled upon the article. You get a pretty good idea just reading the thread here. But, since back issues are still available, I did order back issue. I think...It’s only 6.00

and quote....from PM thread. The link to PM thread is below the quote.

“Again though, I did not come up with this method of repair. I got the idea from the article titled " Line boring a South Bend lathe headstock "in the jan/feb 2007 issue of Home shop machinist magazine. The Author was Jack Butz.”

Fitting bronze sleeves - 9" headstock.

I had a thread going about this but it got lost with the new ubb software change. So from the beginning. A buddy gave me a 9' model A that was ju

www.practicalmachinist.com

And here’s a link to HSM order of Jan/Feb 2007

HSM JAN/FEB 2007

secure.villagepress.com

its a little tricky finding the link on the HSM website.

 

[rwm]

I finally finished building the test stand for my pulse jet engine Filled it with fuel. charged all the batteries, ready to go outside and clamp it to the picnic table for testing, and it started to rain...........They are talking about rain and/or snow most of next week

That is cool. Is there a thread on this?
Robert

 

[Flyinfool]

That is cool. Is there a thread on this?
Robert

Building an RC Pulse Jet Powed Airplane.

I figured I would add in a build thread for a new RC Jet that I am building. I actually started this a long time ago so I will make a bunch of posts to catch those interested up to date. Ya I know this ain't machining related. BUT it sure do look like it will be fun. I just ordered this from...

www.hobby-machinist.com

 

[GoceKU]

Today the digging continue, we put in a full day of work, most of it repairing the mini digger, i don't know who made this caterpillar but its garbage. We had so many problems with hydraulics, then pin from the basket fell out and the cylinder managed to twist the half moon coupler and one of the horseshoe connectors. So cutting twisting welding i did manage to fix it, me and the guy who operates it spent 3 hours on it but once we fixed it it run for an hour straight and made some good progress as you see. But then as it heated up it started to have mind of its own the guy running was phenomenal in running it but it's hard to control something in that tight of space when it is not responding on the commands. We hit the ceiling couple more time and to garage door, this time we put a round hole in the ceiling and pop the door of its rollers. By the end of the day we went thru every hydraulic valve and 20 liter of hydraulic fluid. We parked it inside and closed the door. The guy said he'll try to run it tomorrow but if it's still uncontrollable, he'll take it back to the caterpillar dealer where he spent 1,5k before coming to dig here. I hope you like seeing my strugles.