What's the best slide mechanism for a mechanical hammer?

[Jeff Seelye]

I was looking at several hammer slide mechanisms. What is the best sliding mechanism. I've seen steel on steel, brass on steel. I'm kinda looking for Pictures or sketches if you've got any.

[Judson Yaggy]

My first thought was steel on bronze, but then I realized why mess with a proven design? Every perfectly functional 100 year old hammer I've seen runs cast iron against cast iron (with lots of oil). Lots of folks that do a home built hammer use UHMWPE (polyethylene) for ram guides.

[Jeff Seelye]

Wow, hadn't even thought about CI. Just for wear I was thinkin about bronze. Had a die maker tell me about ampco 18, said it was real good for slides but I couldn't find any. I'm just fishing for plans better than steel on steel.

[HWooldridge]

The better hammers had bronze wear pads - at least on one side. If I were building one, I'd use flat brass strips as the sacrificial surface. In machine design it's typically a no-no to use the same material at the same hardness as wear surfaces. For example, you can use H13 at 48 Rc against S7 at 52 Rc, but H13 against H13 at the same hardness will probably gall under high sliding loads. Of course, the slop in the hammer ways may be sufficient that this will never happen.

[peacock]

Most old mechanical hammers are cast steel ram on cast iron frames keep it oiled and run close fit and it will run for years and years. If you don't keep the clearence tight scale will get in the guides and eat up the machined surface. Then when things get really loose the ram will start slaming around and forge the hammer ways apart.

[Nakedanvil - Grant Sarver]

Surprising as it might sound, most rams in my experience are cast iron. I've had to weld/repair a few (Little Giant, Beaudry, Fairbanks) and they were all cast iron. Cast iron against cast iron is the only one I know that breaks the rule of running similar materials together. Yeah, Ampco 18 makes a good slide.

[pkrankow]

I know the Ajax press I helped on had bronze liners with groves for pressurized grease. Very big machine.

Phil

[twcoffey]

Industrial companies are using UHMW plastics extensively for sliding surfaces. An example is the sliding rotating water screens for power plant water inlets.
The most important factor is that the sliding metal surface must be smooth to prevent accelerated wear of the plastic.

Ted

[arftist]

Cast Iron isn't practical for most home builders. I made a box out of 3/4" cold finished (cold rolled) plate, which bolts together. The box is 1 9/16" inside dimension larger than the hammer in width and depth, and 10" high. I bolted two pieces of 3/4" square bronze bar stock in each corner, with the back two pieces and those on one side being fixed, and the oposite two sets being adjustable with locknuts. I have found oil works better for lubing the hammer slide than grease.
Bearing bronze is available from McMaster Carr, but is very expensive. I used 380(architectural bronze) and it has lasted for many years of hard use. If it ever wears out, like in maybe another fifty years, it will be cheap to replace. Whatever material you use, make the bearings narrow. Too wide will generate too much friction, no matter what lube you use.
If I ever figure out how to publish photos I could write a lot less.

[Jeff Seelye]

Thanks for the replys! I think you see where I am at. Cast iron would be the best but I don't have access to material or machining. I guess my question was misleading. I'm trying to think of what I can do to get started on a hammer without finding out the "better' way after I already build it. Bronze or UHMW are both possibilities but scale and UHMW don't seem to mix well.

[Spears]

I chose to go with Bronze alloy 932. From McMaster Carr a piece can be purchased for ~$150.00. The 1/2" thick 8"x12" will come in about .10" oversized with plenty there to machine down thickness and put in peg supports. Band sawed into 4 pcs 2.875 wide. Supporting inside the sleeve with two 1/2" bolts central with a 1/4" bolt on every corner for support. Back plate bolted solid. I'm building a David Robertson air hammer. Up to this point it seems very sturdy and slides good with thin film of oil. Plastic is probably a bit slicker. Bronze was my personal preference for this contraption. You asked for pictures, but I make no claim this is anything superior to what the professionals have already mentioned. Yeah I know it isn't a mechanical hammer, my bad. Spears.

[Mainely,Bob]

I`m going to jump in here and ask afew questions because I am also in the planning/collecting stages of building a tire hammer.

I know that some sort of lube is needed on any power hammer and that the scale generated will tend to combine with that lube to make an abrasive condition and cause wear.
the favored lube seems to be oil as most folks believe that enough oil will help flush the grit out rather than hold it like grease would.

I`ve seen treadle hammers that use rollers to support and guide the ram but have yet to see any pics of a power hammer that uses them.Does anyone know of any examples that have stood up long term?

The other thing that caught my attention was the UHMW plastic as I had worked with that and Delrin as guides and bearings while working in an aluminum extrusion plant and while it wore out faster than metal the engineers favored it because it was their opinion that the grit imbedded itself in the plastic and as a result caused less wear on the more expensive machine parts.They felt it was cheap enough that it could be considered a throw away or sacrificial part.Most of these plastic parts spent alot of working time covered with drawing oil and it didn`t seem to bother them.
The dry saw guides were being lubed with graphite when I started in an effort to keep them dry and have chips bounce off rather than stick.They were experimenting with spray on dry lubes such as wax and other compounds(Sandaro Dry Slide was one) but I left before they found a product that worked well,was readily available and cheap.
My questions here are does anyone know of a dry lube that could be used with UHMW that would be better than oil?Another question is how does the plastic hold up to the side stresses of a tire hammer ram?

[youngdylan]

Scale bad but my bigger enemy is grinding dust. Workshop is microscopic and I've got a bee in my bonnet about grinding welds smooth. The photos show two kinyons I've built. One is more or less conventional. T'other is KA75ish, but with a pilot valve so it auto cycles. Some of the good things about it, besides the footprint, are the upside down cylinders make for a more balanced air system, which I kinda find much more controllable than the normal Kinyon. The other good thing is the guides. These use easily replacable off the shelf phosphor bronze bushes running against EN24T rods and greased using nipples. The guides have oil seals top and bottom which hopefully keep the grease in and wipe away any grunge before it can get to the bushes..... that's the theory anyway.

I like it so much I keep mulling over the idea of modifying the other Kinyon so the "head" is based around two upside down cylinders, side by side with tup (no off center forces like a Phoenix) and a similar "sealed" and easily maintained guide system. Might happen one day.

My other hammer is a 40kg Anyang bought from John N. It rocks. Puts my Kinyons to shame; power wise.

[Jeff Seelye]

Thanks for the replys folks! I think I am headed for the two metal system. Heck, I even liked the air hammer inputs. Good slides are good slides! Arftist, with discriptions like that... who needs pictures!

[unkle spike]

My slide on my Appalachian Style is Mild steel tube-in-tube. I just use plenty of Moly Grease on it. Grease is cheap compared to replacing parts. I thought about bronze or teflon for bushings, but opted for a light loose fit, and grease it often.

I recently updated with a 2" square tube filled with lead shot, then heated to melt the lead into one solid mass.

[JNewman]

My kinyon style hammer is a bar in a tube when I built it I lined the tube with UHMW and put in adjusting bolts to tighten it up as it wears. 10 years in and after a lot of (ab)use most of the adjustment bolts have long since fallen out and I have never had to tighten them. I OCCASIONALLY give the ram a spray with some dry moly spray. I would highly recommend UHMW for a home built hammer and advise running it dry or with a dry lubricant. I have never had a problem with scale getting into the plastic.

[JNewman]

The UHMW on my hammer is only 1/4' thick I wanted to maximize the size I could make my dies.

[Jeff Seelye]

Now you have me thinking. I was scared to try the UHMW and didn't want to waste my time if I was going to have to tear it down and change it. I like your "(ab)use", I tend to push tools sometimes also and I tend to overbuild because of that. How did you attach the UHMW?

[monstermetal]

This a great little bit of info.... It sure nice to have a place like this to see what has or has not worked for others... Where else would we get the kind of instant feedback and diversity going on here!

[JNewman]

I just drilled and tapped holes in the tube and then used flat head machine screws countersunk into the plastic. If it will fit heavier uhmw would probably bulge less around the screws. I think I used loctite on the machine screws because they have not shaken loose. They would be a pain to tighten if they loosened up.