Furnace Cart and Lift Build

Finished up the lid lift today.





Need to work on the ballast carriages tomorrow.

Best,
Kelly

 

Thanks Guys. I can be a bit obsessive at times but I do enjoy it and I usually get something useful out of it all. I must say, casting and machining all those pulleys/guide wheels, and mounting brackets was a bit of a grunt. It may be a slight bit Rube Goldbergish, but gravity is pretty darn reliable. Let's see how the ballast carriages go today. We got a foot of wet snow yesterday. I cleared the first 6" yesterday because I didn't think my blower could handle a foot of that wet heavy stuff so I have the rest ahead of me this morning before I hit the shop.

Best,
Kelly

 

After blowing snow and some honey-dos, I got out to my shop and finished up the ballast carriages. The post on the single wheel is drilled eccentric so it can be adjusted to the desired clearance.




I wanted to test the lid lift first. Back in post #9 I remarked about combining the guide wheel and lifting pulley would require the guide wheel to slip on the post because the different contact diameters of the cable guide chamfers and the doubling block would require the pulley/guide to spin at slightly different speeds.





It works but I’m afraid it’s not going to work satisfactorily. If I have the guide wheels adjusted against the posts, it causes the cable to jerk, slip, and grab during motion and if I loosen the guide wheels so they slip, it creates some sloppy motion and minor wracking. This will be worse on the furnace body lifting because its weight will mean higher contact forces and those aluminum wheels already grip the steel post very well on the lighter lid lift.

I left myself two provisions to address this; direct lift the lid and body without the doubling block, or add separate independent lifting pulleys for the doubling blocks.

If I direct lift I can get more lift height but will need to use twice the ballast weight. I don’t need the extra lift height and it will add 100+ lbs to the overall weight of rig and a higher center of gravity. The only downside to using separate lifting/doubling pulleys is I need to make four more pulleys! I’m going to have to sleep on that one. I’m leaning toward adding four pulleys and staying with the doubling block arrangement.

Best,
Kelly

 

Good grief, that's absolutely right. I didn't even give a thought to direction of rotation. What a gaff. LMAO.

Yup. think you've got it. I could do that on the lid lift but the way the cables must be routed and nest, I could not do that for both the lid and furnace lifting on the current layout.

Also a good thought but aside from the fact I don't think the existing pulleys could be re-worked as such, not sure I have room widthwise to pull that off.

When I was spit-balling the cable and pulley arrangement I thought it might be nifty to combine the pulleys and lifting wheels but I knew there was a potential problem using the same pulley as a guide and as the doubling block lifting pulley. I was so fixated on the difference in pulley and guide diameter, I completely overlooked direction of rotation. Even with correct rotation, if there is a difference between the contact diameter on the post of the guide wheel pitch diameter (GwPD) and the cable pulley pitch diameter (CpPD) it means the center of the wheel wants to advance at both Pi x the GwPD and Pi x CpPD. Since the two can’t be the same diameter there will always be a mismatch and there must still be some slip of either the cable or the rolling surface. Reverse rotation takes slip to a different level!

Even with correct rotation it’s sort of interesting because the degree of mismatch depends on where you think the pitch diameter lands on the guide wheels. Is it nearer the root of Vee or at the OD? Or in between? The OD is 4” whereas the cable pulley diameter is 2 ½”…….that’s a big mismatch whereas if the GwPD is near the root it’s much smaller and requires less slip.....but me thinks it is now a moot issue.

I think the most practical solution as rework or maybe even at inception having recognized the counter rotation would still the same, direct lift or separate lifting pulleys.....still leaning toward the latter since everything else is built and added pulleys are fairly easily accommodated.....famous last words.

Humbly,
Kelly

 

Wasn't planning on doing that until I disassembled everything for paint. The big pulleys are just guide wheels and probably don't need it but once the cross slide on the lathe is set up, may as well true them all up. The small pulleys on the ballast carriages will benefit quite a bit from being trued up since the distance between centers across the post is fixed and any eccentricity and run out there is very noticeable in the ballast carriage rolling motion on the post.

Not so sure about that. There are hollow axles on each guide wheel with a 3/8 bolt running through them that get sandwiched between the mounting plates. That's how they are adjustable on centers and fixed in place, but I think you'd need to control and maybe even shim the stacked clearance pretty closely because clearance needed on the axle for the holes in the plates would also allow them to spread and deflect and maybe bind on the axles. The cable from the furnace body lift is routed through the grooves in the lid lift guide wheels but isn't supposed to engage them so I wouldn't want to cut guide grooves into those lid lifting pulleys and the lid needs to operate independently from the body. I have mounts on the lid pulley brackets to install slotted/adjustable plastic cable guides to get the cables spaced and to track more precisely in the vicinity of lid lift guide wheels because without, I think they actually would tend wander. I'm also thinking at this point four more lifting pulleys sounds like a sure bet and much less rework......

^Thanks OIF. Such a fundamental error in kinematics.....tisk tisk. I can remember plenty of times trying something that didn't work as well as expected but can't remember getting this far down the road with something that was never going to work. Appreciate the suggestions. Would have been even better after post #1, where were ya? . Bare with me. Recovery and hopefully redemption is coming.

Best,
Kelly

 

I trued up the pulleys and guide wheels on the lathe and added the lid lift pulley mounting slot tonight. For the added slots I had to drill holes, connect them with the recip saw, and then tune them up with a die grinder and burr. I’ll be picking metal slivers out of my hands for the rest of the week. Truing the guide wheels really made the motion of the ballast carriages much smoother and precisely guided.

Any time I can take ground on a week night is a good night. I hope to have the lift working this weekend…..must have goals!

Best,
Kelly

 

Thanks for the tip. I was rifling through those pulleys as fast as I could over my lunch hour and just grabbed whatever tool was laying on the lathe......but my very limited machining skills are further aggravated by impatience.

I cast in the axle holes in the pulleys but unless you're going to use a small boring bar, it's tough to have the concentricity necessary to just drill and ream for bushings since the drill just tends to follow the holes then your reamer will cut over size. Those holes were mounting provisions for machining the patterns but I probably should have plugged them, center drilled, reamed etc. Close enough for who/what it's for.

Funny thing, I took the lost foam exit ramp and never got back on the casting highway. Eventually I want to build a muller and have good molding sand. I have shell material and wax, and would also like to do some investment casting and other metals too. Every process has its strengths and place. Crazy thing is I can do most everything I need with lost foam and very quickly. It's tough to beat for making one-offs or handfuls....have you read the pros/cons thread?

I'm enjoying a lot of family and shop time this weekend and will have an update for this thread in the near future.....maybe tomorrow night if can get to posting it. Gonna have a casting session tomorrow morning.

Best,
Kelly

 

I coated everything including the bores with drywall mud because it keeps the sand from imbedding in the surface of the casting which as you've noted is hell on machine tools. What drywall mud doesn't fall off in water quench usually blows off with compressed air, or in the most stubborn of cases with wire brush/wheel. In any case drywall mud is much easier on tooling than sand. I've also learned there is no benefit whatsoever in thick coating; it just lengthens drying time. Thinning to the right viscosity is very helpful but you really only need enough coverage to turn the foam from pink to white and this is beneficial in venting as well. Mud is porous and breathes and even more so when thin. The surface finish of the casting is unaffected by coating thickness as long as there is coverage.

Drywall Mud coating has no appreciable strength by itself and wont work as shell without support of the vibrated/compacted sand.

Lost foam Aluminum machining fixtures are very practical but iron is actually superior because of superior dampening as it has a higher elastic modulous......but if it's a stout fixture or doesn't have heavy tool loading it doesn't matter. Zamak (Zinc-aluminum+) alloys are actually a nice compromise because their as cast strength can be comparable to or better than heat treated aluminum and they dampen better. Zinc is cheap and melts below aluminum temps so is practical and easy to work with. This has the makings of another thread!!

Best,
Kelly