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Designing a 50lb guided helve hammer.

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I'm planning to build a guided helve hammer with preclutch flywheel, similar to arftist's:

My goal is 50lb tup, 220bpm.  I want it to be stout, efficient and minimize transmitted vibration/noise. Cost is important, but not paramount(I'll be buying new parts as needed rather than scrounging forever). In case of a later increase in head weight, I don't mind overdesigning some parts. I'm trying to get an idea of how beefy the mast and drive systems' bearings/shafts need to be for 50lb tup and how that would change for say a 100lb tup.

Here's the 50lb design parameters.  Feedback appreciated!

Pivot: 2 inch diamter shaft and pillow block bearings.
Push rod: 3/4" round (or 1" thick wall pipe?) with 3/4" turnbuckle
Push rod bearings at bottom and top: 3/4" spherical rod end bearings.
Pitman crank: 14" diameter, 0.5" thick
Pitman bearing/shaft: 1.5" diameter
Intermediate Jackshaft diameter: 1"
Flywheel: 16" diameter, 1" thickness
Anvil: planning on laminating thick plate for at least a 15:1 ratio.
Spring: 2" by 5/16, 40" main leaf, 24" supporting leaves.
Guide: UHMW strips, similar to Don S's guide: http://www.wcbg.ca/wcbgsite_015.htm, using 1/2" front plate.  I've seen some guides calling for 1" plate in the guide. At what point does this become important?
Mast: ???.  I currently have 12' of 6"x6"@15 H-beam(1/4" thick) but I believe I may look for some wider/heavier beam. 
Base: 1.5" thick, approx 2.5x4 feet. I may weld together 2-3 pieces of thick flatbar lengthwise (for example 2 pieces of 1.5"x16"x48") because it's difficult for me to acquire and move large pieces of steel. Thoughts?
Foundation: I'm building this is a residential detached brick garage in Toronto, Canada. The floor slab is 3" and cracked long ago.  I plan at a minimum to cut the concrete around the base to isolate it from the rest of the slab, then rubber/timbers as appropriate.  I may dig and pour a new thicker foundation.



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My mast is two I beams welded together to form a box flange edge to flange edge. 

For you main pivot suggest you turn down a larger shaft at each end to the bearing diameter instead of relying on set screws to prevent side to side movement.

My tup is 75# and I used a 1" turnbuckle. Better is a rod sliding in a pipe with a clamping bolt.

Turnbuckle is very slow in comparison.

I used bronze slides instead of plastic...suggest you do the same, much stronger.

Made my slide from 3/4" cold rolled plate wouldn't reccomend much less.

1.5" base plate does not need reinforcing, waste of time.

Laminating plates horizontally will waste much energy verticul is fine but not ideal.

How are you planning to transmit power from jackshaft assembly to your pitman crank? 


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Thanks for the feedback. I plan to use flat belt, for sake of smooth control. Although V-belt components would be easier to source, does not seem ideal in a clutch mechanism.  I plan to fabricate any pulleys I can't source from pipe, plate and weld-on hubs.

I'll use 4-ply cotton/rubber from McmasterCarr. What's the width of your belt? 2.5" would seem adequate in my case.



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Flat belt pulleys need to be crowned. 

You have a lathe? 

Mine is 3" but not an issue. 4 ply power transmission belting

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I don't have a lathe, but my plan was a makeshift "lathe". Turn them on an axle and crown the edges with an angle grinder/flap disk.  Same for the flywheel. Torch cut 1" plate with a circle jig, then spin it and grind it true as possible.

Not a good idea? Otherwise I'll find some one to help with machining.

Besides the previous thread, do you have any other photos or videos of your hammer arftist? Would love to see it in action.


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Why not use a flywheel off of something like a truck? 

An inexpensive way to get a flywheel flat would be to hit up an automotive machine shop and have them do it on their flywheel grinder...


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Unless you have machine shop skills your plan for crowning the pullies is a whole lot more work than you think and it's worth. Even with good shop skills it's more trouble than it's worth. Sure it's doable but I'd get a job shoveling driveways, save and buy what I need. I have a lathe and the skills.

6" 15lb. wide flange isn't going to be rigid enough, even doubled is going to be a little flexy.

We LOVE pics you k now, keep us in the loop please.

Frosty The Lucky.

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my 70# guided helve hammer uses a compact spare tire as bot flywheel and clutch. Works very nicely. Used a 1990 Gran Caravan rear axle bearing hub assembly. It bolted to the axle and so I just unbolted the entire bering hub assembly took the spare tire and another wheel from the junker. The hub assembly bolted onto the hammer frame using the original bolts from the van. I cut the center from the second wheel and used that to weld a bottom for the pittman to and then just placed it over the compact spare. Has been running since 2005. I started at 32# and the Vee belt drive sorted of worked. Upped the ram to 45# and smelled burning rubber and it was jerky as it needed a flywheel. Went to the tire clutch. A couple of years ago I upped to 70# and changed the ram guide to mostly mirror the tire hammer slide design.

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Thanks for the feedback guys. I'll likely reconsider fabricating the pulleys and flywheel.

Biggundoctor my automotive knowledge is limited.. i had dismissed vehicle flywheel as too small/light. I suppose I could stack a few of them.  I calculated that a 60lb disc shaped flywheel (1"x16"diameter) at 800rpm stores 2000 joules, or 2.5 horsepower seconds. Not sure exactly how that behaves in practice, but seems like it's in the ballpark.. flywheel energy could theoretically replace the 2hp motor for a second. 

Frosty, point taken regarding it being more trouble than it's worth.  But then again, one could argue building a power hammer is more trouble than it's worth :)  I might be stubborn and experiment anyways, because I find it fun/motivating, and because I'm at the point that I can still learn a lot from the process, regardless of the outcome. In any case I'll share the post-mortem here.  I'll definitely also post photos of the build in general. 

Ptree, not sure if I understood completely, but are you using a 2nd tire as a flywheel pre-clutch? I want to try to avoid the tire clutch mechanism that has the motor directly driving the wheel.

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For your center mast go thicker than 1/4'' it will twist and the flywheel off a diesal is heavy i made mine 14'' circle out of 1/2'' plate i used 1/4'' for my mast on the proto type it twists to much i had to anchor the top to my wall.Its 50# head works great but theres some things i got to work out for the next one.Put up pics of your ram slide mine is steel on steel thats where my biggest prob is were thinking of goin with some kind of roller system to keep it centered better on the next one.This one is the proto type next one will be bigger and painted if your curious i got a pic of it in the gallery.

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Question regarding spring deflection: to design dimensions, I need to know how much clearance above and below the ram guide to factor in for stroke plus spring deflection.  I tried calculating it theoretically, but from others experience, how much overshoot can I expect?

5/16" thick, 2" wide. Main leaft 40" long, sandwiched between two 20" lengths.
7 inch stroke (3.5" from center of pitman crank)

I calculated the spring constant to be about 14000 N/m.  For a 50lb at 220bpm, I calculated the force on the ends of the spring during normal operation to be about 1200N, which would mean 3.5" deflection. 

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I will measure my hammer later and post the actual butI think it is 14"

If your larger pulley is crowned your smaller  one can be flanged.

I used a piece of 14" steel pipe  and crowned it 2 degrees .

If you fab it up a friendly machine shop might crown it for a reasonable price. 

The flat belt clutch works so well that it is worth it.

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Pouring the foundation

In the last couple of weeks, I prepped and poured the power hammer foundation.  Although probably not necessary for a hammer of this size, I want to do all I can to minimize vibrations as I'm in a residential area: heavy isolated slab of concrete, 2 inch baseplate, and 15:1 anvil/head ratio.

I started by choosing the position of the hammer.  Roughly in the middle near the back wall. Dies will be on a diagonal to maximize working length.  The floor in my garage is very old 3 inch concrete, cracked in many places. Rather than renting a concrete saw, I just drilled holes and broke it up with an 8lb sledge.  That took a lot of effort. Good striking practice, part of my exercise regiment. 


Benefit was that there was minimal dust (compared to a dry cut saw) or gas fumes. Dug down 16 inches, compacted the dirt.  Filled the bottom 4 inches with gravel.  Lined the sides with wood and fiber expansion joint. Placed a 'rebar' cage (some scrap twisted square bar). Cavity is now roughly 30 x 55 x 12 inches.  Debated putting in an assembly for T-bolts, but decided to just keep it simple.  If I even need to bolt the hammer to the foundation, I'll expoy in some all thread.  Likely will probably just attach some pins/supports to keep the hammer from moving around.



Debated between renting and buying a concrete mixer.  Needing to maximize flexibility in scheduling : when it came time to pour, don't want to waste time driving to/from the rental store. So I went ahead and bought the harbor freight equivalent here in Canada of a 3.5cf mixer.  Assembly was not too bad.

Got everything ready the day before the pour. 30 60lb bags of high PSI premixed concrete, mixer in place, hose, compacting and forming tools. Note that I've never done any of this before.  I have to plan things well to wrap in time, as I only have max 5 hr blocks of time before picking up kids from preschool.  I calculated that should be plenty of time.  


Day of the pour, everything seems to be working well.  Mixing with minimum water for maximum strength. First 10 bags take less than hour.  Then the mixer quits!  I keep calm and troubleshoot. The on/off switch has vibrated out of its housing and come apart into pieces.  Fortunately I was able to fix it relatively quickly. What a bummer that would have been. 


Rest of the pour went fine.  I had worried way too much about having the wooden form perfectly level.  Turns out that mass of concrete will do a good job of leveling itself out.  Smoothed it with a 2x4 and then as it hardened with a small trowel. In the end was 24 bags so upwards of 1500lb.  


For the past 7 days, I've been keeping it wet and covered with plastic.  Base plate won't come for another couple of weeks, so will keep moist curing until then.

Progress feels good!  I've never worked with concrete before, it was pretty fun. Definitely a work out doing it on your own, but for someone who spends most of their time in front of a computer, it's great to be doing something physical, working with real materials and tools. More to come.



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6 hours ago, tylerdewitt said:

I've never worked with concrete before, it was pretty fun. Definitely a work out doing it on your own

Next time use a hoe and a wheelbarrow, that's when you really get to have fun. :) 

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Fabricating flat belt pullies and flywheel

My hammer will use a flat belt clutch (4x4 and 13x4 pulleys) with a pre clutch flywheel (16" diameter, 60lb). I initially puzzled over how I would acquire these parts:

1. I could try to scrounge for them, but that would take forever and probably wouldn't find my intended dimensions, introducing compromises/contraints in the design.

2. I could buy the parts or pay to have them made. But then I will only have those parts. If they wear out, or need to be redesigned I'll have to shell out again.

Finally I realized I should just give a go at fabricating them.  I wouldn't necessarily recommend this.. I chose this approach because this is a kind of personal DIY journey.  Time consuming mistakes will be made, tools/raw materials will be purchased, but in the end I'll (hopefully) have the parts I need, and (definitely) will have gained skills, experience and tools that will surly be useful in a blacksmith shop.  Plus, it's really fun.

So I bought some plate and pipe and got to work.  I had a first failed attempt at the 4x4 pulley. I torch cut a hole in some 1/8 plate (too thin, warped) for a weld-on hub, then attempted to weld this and the pipe together concentrically just by laying out with a ruler.  Of course it didn't work.  When I got to spinning it on an axle it was noticeably out of center.  I tried truing with an angle grinder while spinning at low speed.  The surface got smoother, but the part did not get much more concentric.  The grinder just follows the surface rather than selectively removing the high parts.

Since then I've done the right thing: acquired a 10" x 18" lathe and spent some time learning some machining basics. That's a whole story in itself, but suffice to say it will help with the 4x4 pulley (as well as rollers, idler etc), but the 13" pulley and flywheel still needed to be fabricated.

Next attempt was the 13" pulley. Drilled a few holes then torch cut rough hole in 1/4 plate for QD bushing.  Filed holes for bolts and secured bushing.  Mounted a bearing and axle vertically, placed a slice of 13" pipe on the plate and rotated with a dial indicator while adjusting for concentricity.



The jig was using only one bearing and had runout, so switched to a setup with two spaced bearings.  Found the low point on dial indicator, tapped with a mallet. Got it to within about 10-15 thousands before welding in place.  Torch cut the corners of the plate off and ground smooth. Rough cut a 1" hole at 3.5" off center for the crank pin. Mounted it horizontally, and lighty sanded it with a 4" belt sander while turning. As it stands, pulley is not crowned, but I will later attempt to grind/sand a taper on the edges.






Here's some shots of similar process for my 2nd attempt at the 4x4 pulley. Cut holes in plate and welded on the hubs.  Set everything up on bearings and axle. The pipe is held by friction between the two plates, adjusted by tapping with mallet while reading the dial indicator. Tack welded in place.  Sawed of the corners.  I'll finish it up on the lathe.


The flywheel is 15" diameter cut from 1 inch plate.  I started by drilling a few holes.  (Note: I pickup up a nice used mag drill around the same time I started this, and I'm sure glad I did.  I doubt much of this would even be possible without it,  at the very least makes life sooo much easier ) Rigged up a circle jig for the torch.  The circle jig didn't work incredibly well, but it was good enough for the mounting hole. Drilled some bolt holes and secured the bushing.




Next came the fun part.  I wanted the flywheel as true as possible without requiring machining/ginding.  I thought about different ways to do this.  I decided a circle jig wasn't going to cut it (hehe) and opted instead to keep the torch stationary while spinning the workpiece.  Mounted the plate on axle/bearings. Torch tip fits snugly into a half inch hole in some flatbar clamped to the table.  Checked everything was steady, did a test movement run before lighting the torch. There was a lot building up to this moment.   While the sparks were showering, have to admit I got a pretty big rush. Oxy-propane torch is powerful tool, and wielding it to cut a wide perfect circular arc through inch thick plate like a hot knife through butter was amazing fun.  Had never torch cut material of this thickness before.




Removing the circular fom afterwards took longer than the cutting.  Had to chisel in some places and beat on it for a few minutes to dislodge. End result: 15.5 diamter,  about 55lbs.  It will spin at about 650rpm.




And here are the machine parts. Took some time, but feels worthwhile.



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This is great, I have dreams of machining my own castings or forgings at some point, like you I like the whole process as much as the destination.

Great problem solving and man I really want a mag drill :) there's been one on cl locally for 6 months now but I just can't drop $500 on a single tool right now.

Keep learning and sharing!

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Unloading some heavy steel

Had some large pieces of steel delivered today, notably a 2x28x42 plate weighing 700lb. I was responsible for unloading, and was a little nervous having never moved anything of this weight before. I prepared in advance by building a sled and testing it on 1.5" PVC pipe rollers carrying the heaviest items I have.  Gratuitous anvil shot:


Delivery came in a pickup truck. I was prepared with engine hoist and tow cable. The delivery guy was friendly and helped me rig the hoist.  All went smoothly. Plate was on a skid so I didn't need the sled.  There are some additional smaller pieces of plate bundled, so the total weight was close to 1000lb. Lowered it onto rollers and pulled it into the shop.  Pretty easy on rollers! Reminded me of the strong man competitions where they pull an airplane.




Concrete has been moist curing for 2 weeks so I decided just to put the plate in place. First a piece of half inch plywood, then rolled the whole skid on top. Used the engine hoist to lift just the plate, then removed the skid and rollers and set it down on 2 blocks, to allow removal of the tow cable before kicking out the blocks. Actually i used a hammer because I value my toes.  It was a pretty satisfying sound when I tapped out the last block. Kathunk. Zero rebound movement, like in the cartoons when they drop the anvil on Wiley Coyote.





Also part of the delivery were two 66" long [email protected] beams for the mast. These were pretty simple by comparison to move and unload. Overall I found the entire move wasn't nearly as difficult as expected.  If it had been top heavy, fragile machinery it would be a different story.  But big chunks of steel rig and roll easily.


I didn't order steel for the anvil for two reasons. First, to test my abilities unloading, and second to see what kind of cut edges I have to deal with.  The base plate appears to be CNC plasma/torch cut, and it's smooth and accurate.  The beams and 1" plate pieces were saw cut, and not perfecting square.  I'm choosing between laminating 1" plate vs a solid anvil. Laminating would be cheaper, but that's a lot of welding and grinding, and the plates will not be perfectly aligned to begin with.  Might opt just to buy a solid piece, now that I feel more confident unloading 1000lb.

Starting to look like a hammer now.



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I was sidelined for a while by a noise/zoning issue.  City bylaw officer showed up at my door stemming from noise complaint.  Long story short, it essentially blew over. I did some sound proofing and the build continues.

Top Pivot
The pivot is 2inch pillow block bearings, attached with bolts to threaded holes in a top plate.  The top plate bolts to the top of the mast with through holes.  This will allow optional spacer plates to be inserted beneath to raise the pivot, per arftist's design. I'm also keen on being able to disassemble things if I need to modify or move. The ubolts are bent from 5/8 threaded rod.





Drive System

The bearing supports are fabricated from thickwall tube and clamped/spot welded to the frame; welds to be finalized at a later point after I'm satisfied that everything fits and works. I spun the jack shaft with a small motor and trued the flywheel with a flapdisc. It was already very close, just the kerf from the torch cutting. It spins true at 800 rpm with little to no vibration. 






Pitman Arm
The pitman arm is 1 inch threaded rod with spherical rod end bearings on each end. The pin is a grade 1 inch grade 5 bolt that passes through a spacer to allow clearance and extra support.




Treadle and Idler

I machined an idler pulley from 1.5 inch thick walled pipe. I don't really know the range of motion necessary to give adequate tension, so the treadle construction is kind of an experiment, hence the spot welds until things are finalized. Bolts for treadle pivot, spring return.




Flat Belt setup

I positioned the idler to just touch the belt when treadle is up. Treadle down it jabs inward 4-5 inches.  I cut the flat belt long and joined the overlap with duct tape while I get a feel for the tension required. I tested by manually spinning the jackshaft flywheel and engaging the treadle. I had used a flapdisc to put a light crown on both pulleys, and best I can see now tracking isn't terrible, but decided flanges on the idler and smaller pulley could help. The flanges were forged and welded.





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guide box


other veiw

this shows the adjustment 


side slide adjustment 


the socket head bolts thread into the bronze guides.

The set screws with lock nuts thread into the box and end in blind clearance holes drilled in the bronze.

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method of riggng foot petal without springs

the pivot point must be placed where the idler wheel end is heavey enough to return on it's own.



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Some photos from the past six months.  3HP motor with VFD. Guide box with brass bearings, per arftist's design. Vertical position of entire guidebox is adjustable with evenly spaced holes in backing plate.  Anvil is 12x12x30, overkill arguably. The ram is currently about 85lb, cycles at about 170bpm, very stable, very little vibration. Splintered some 2x4s today.

Many tunings and improvements to be made, but very close now to having a working hammer.  







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12x12 hot rolled, plasma cut. Supplied through Metalsupermarkets, I'm not sure who their supplier is. It was embarrassingly expensive, but they helped with delivery and unloading, and it was a no brainer solution to some of my constraints.  The hammer runs rock solid, neighbors won't feel a thing. I'm sure I could increase the ram weight.

I've been running it a bit the past couple of days with temporary mild steel dies. Had to make some adjustments to the spring pack, add spacers and stops to keep some parts from slowly shifting/sliding around. Once settled in, I'll try to share some videos.

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