Todays Project - What did you do today?

[dallen]

(03-22-2014, 05:14 AM)awemawson Wrote:

(03-21-2014, 08:06 AM)dallen Wrote: home mixed oil bonded sand, and a two part mold. Oil bonded sand is hard to work with when its cold so the first one that I poured was a little rough around the edges, the second was a lot better pour but I lost the bearing in the back of the vac motor I use for a burner blower so melt was really fun with a half a crucible full of half melted aluminum when the blower gave up the blue smoke.

Is it your own recipe and can you share it ?

same recipe that everyone else uses far as I know , petrobond powder and used motor oil with a splash of Methanol throwed in to catalyze the oil, all mixed up with some silica sand.
Stuff is a bear to work with when its cold, but when its a hundred degrees here I don't have to worry about molds drying out faster then I can ram em up.

DA

[roundrocktom]

Need to cut some small 1/4" steel with a small angle.

I can tilt the head, but that takes a while to dial in, then dial back when done.

Spotted a "mini pallet" on Tom Liptons youtube video. Hmm, add a round stock, simple to tilt. Cut a hunk of 2024-T3 1" thick I've had for ages. Cut to 6" x 8".

Drilled 48 holes on one inch grids. 16 for dowel pins for locating work. 32 drilled and tapped holes for clamping.

Work in progress (need to add a Hermann Schmidt type of side clamp)

[dallen]

the things we do for our friends, a buddy of mine ask me to thread him up a hunk of round bar so I said yes then he lays it on me, damn old scaffold jack screw. things all banged up but he did brush most of the rust and concrete off of it.

Anyway I got the threads in it, not as pretty as some I've done but not to bad I think.


   

   

   

[awemawson]

(03-22-2014, 11:04 AM)dallen Wrote:

(03-22-2014, 05:14 AM)awemawson Wrote:

(03-21-2014, 08:06 AM)dallen Wrote: home mixed oil bonded sand, and a two part mold. Oil bonded sand is hard to work with when its cold so the first one that I poured was a little rough around the edges, the second was a lot better pour but I lost the bearing in the back of the vac motor I use for a burner blower so melt was really fun with a half a crucible full of half melted aluminum when the blower gave up the blue smoke.

Is it your own recipe and can you share it ?

same recipe that everyone else uses far as I know , petrobond powder and used motor oil with a splash of Methanol throwed in to catalyze the oil, all mixed up with some silica sand.
Stuff is a bear to work with when its cold, but when its a hundred degrees here I don't have to worry about molds drying out faster then I can ram em up.

DA

Thanks Dave.

I think Petrobond is much more common your side of the pond than here. I can buy petrobond bonded sands relatively easily but at a huge price of about £1 per kg plus about the same for carriage, but the petrobond powder doesn't seem to be available here to make your own. Unfortunately this makes petrobond a very expensive option.

[dallen]

(03-22-2014, 01:50 PM)awemawson Wrote: Thanks Dave.

I think Petrobond is much more common your side of the pond than here. I can buy petrobond bonded sands relatively easily but at a huge price of about £1 per kg plus about the same for carriage, but the petrobond powder doesn't seem to be available here to make your own. Unfortunately this makes petrobond a very expensive option.

bentone 34 is what Petrobond powder is made out of, its used as a thickener in paints an such, also used in the oil field in drilling mud which I doubt that they do much of that around you neck of the woods.

do a google for K Bond sand, I was told not sure how true it is that they were going to stop making petrobond, I doubt that they will though.

DA

[PixMan]

Got about 4-1/2 to 5 hours in the shop today. First order of business was to make a HSS internal threading tool for the 1-1/4"-5ACME nut I have to make out of 660 bronze for Darren's Kondia machine rebuild. As seen in earlier posts, the mating threads on the screw itself is done and that will act as the thread gauge.

I roughed it out by hand on a bench grinder, then went to work on my surface grinder. Using the 5" sine bar grinding vise I'd made as my senior class project in vocational school (1976-1977), I first ground the two 14.5º angles. Set the 2" long 1/4" square blank in the vise jaws at 14.5º with my Starrett No.359 precision bevel gauge, then tipped it with the sine feature. One of the few times I get to use the No. 154 adjustable parallels. Here's a photo of the final surface, the tip. It's set square in the vise, then tipped 18º as that 2-1/2º extra clearance below the cutting tip.



I have ground tools like this by hand many times before, but now that my eyes need help with looking close and I have a surface grinder, wheels and tools....
Here's the tool, though I did later add a pair of grooves on the top for the set screws to grip in the homemade bar I'll be using:



Now to rough out the bronze. I chucked the 6" long Ø 3" blank, faced it off, turned both the 42mm and 70.9mm diameters, drilled, bored and chamfered to 1.280". Since I used a flat-bottom carbide insert drill, no excessive waste on the blank!



Turned it around, faced to length and chamfered the opposite end:



Tomorrow I'll set-up the new threading tool and have at it. Hopefully, this one comes out right the first time, not like the screw that took 3 tries to get it right. If I get the lathe work on this bronze nut done I'll try and get the holes done, then finish the work on the fixed end of the screw and SHIP IT!

[Mayhem]

Thanks Ken - that looks way too nice to use (but I will of course). I look forward to seeing the next instalment once you have recovered from your surgery. Nice job on the threading tool. Tom will be mighty impressed

[Mayhem]

Dave - nice job on the scaffold jack screw.

[PixMan]

Finished the bronze nut today, wish I hadn't had trouble with various issues. The nut fit onto the mating screw snug, and I screwed it in until there was about 3/4" of and inch showing through. I took the nut out of the chuck thinking it would run down the whole thread, not so. I had to put it back in and take another thousandth or two. That's a pain in the butt!

To line it up again I had a idea that worked perfect. I had left the tool setting at the last cut, though I had taken the part out and had shifted the spindle speed. To line it up again I put the part in the chuck, started the spindle and engaged the half nut. Using the spindle brake to stop just out in front of the part, I loosen the chuck and rotated the workpiece (nut) out onto the tool. Once the tool was fully engaged in the part, I snugged up the chuck.

It worked nearly perfect. Certainly got me closer that I could have gotten if I tried to line it up the conventional way with moves of the compound slide. The one pass I made took perhaps .002" off, and now the nut sails onto the screw all the way. It's just tiny bit more clearance than I'd hoped to get, but it'll be fine. Because the knee isn't counterbalanced all the force will always be on one side of the thread flank.

After finishing the internal 1-1/4"-5ACME thread, over to the Alliant-Prototrak milling machine for holes. First up, a three hole pattern. Drilling the pattern is super easy with the Prototrak control. Enter in the number of holes, the bolt circle radius, angles between the holes and off you go. A little harder is "circle milling" the counterbores. I don't have a 17/32" end mill not counter bore, so I simply recorded the coordinates used for drilling the holes and used that for center points for three circle milling cycles. I used a 3/8" end mill. My first pass came out at .526", though Darren had .530" on his print. Easy enough, I just edit the program to tell it the hole isn't a .265" radius, change it to .267" and it makes the hole bigger by .004", as seen in the 1:00 long video.





Here's a few finished photos.




Came out pretty good, not absolutely perfect. At least there's no chatter anywhere on the threads and it meets the print requirements. I'm happy with it, just wish I could have gotten to finishing the remaining features on the mating screw.

[Mayhem]

Thanks Ken - that nut looks awesome and I owe you big time for helping me out with this