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This is an archive of posts from June 23 - 30, 2012 on the Guru's Den
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forge : How do you make a good forge?
   Tyler Juneau - Friday, 06/22/12 23:23:00 EDT

Forge :
Tyler, First you need to know what kind of fuel you have available and how big of work you intend to make. Forges burn charcoal, coal, propane or butane, natural gas, diesel fuel or heating oil and waste oil.

Coal: Most blacksmiths will agree that a coal forge is best. Coal is flexible (large and small fires) and burns very hot (up to 3,200°F). It is the easiest forge weld with. But good coal is no longer distributed in most places so you must order it and have it shipped in 50 pound bags by UPS. Depending on where you are this more than doubles the cost of the fuel with $15 to $30 shipping.

If you have a local coal supply you should always test it unless you know a local smith that can vouch for its quality. Coal comes in infinite variety. In some places low grade coal is sold for landscaping color. . . in others it is for stoves and furnaces that do not need to burn as hot or clean as a forge.

A good place to start is with a cheap forge built from junk, a brake drum forge. This will also teach the basics of coal forge construction. To build a first class coal forge it is best to start with commercial components (firepot, blower, control gate).

Charcoal (the real stuff, not pressed briquettes) is the next best forge fuel and has been used for millennia to fire ceramics, smelt metal and other high temperature uses as well as forges. Real charcoal is often available in big box stores and restaurant supplies. If not if can be made if you have a supply of wood and live in a rural area.

Making charcoal takes room and makes a lot of smoke but it is a very clean burning in the forge. Charcoal forges are very similar to coal forges but need to be a little deeper.

Gas: If coal and charcoal are not suitable then most smiths are using gas forges. Propane is readily available almost everywhere worldwide. Many smiths build their own gas forges including burners. Others buy burners and build the enclosure. The disadvantage of gas is that it does not get as hot as coal and you need different size forges for different size work.

Oil: Forges using oil are more common in industry than in small shops but some blacksmiths use oil forges. These are similar to gas but do not burn as clean. They are also more difficult to start and maintain but they burn hotter than gas.

All these choices depend on what you want to do, what your budget is, where you are located. Solid fuel forges can be a hole in the ground, a large steel device, masonry (brick - stone) large or small. But all do the same thing, they hold the fuel so air can be blown into the fire to make it hotter.
   - guru - Saturday, 06/23/12 23:46:40 EDT

Civil war era anvils : Greetings: I have a couple of anvils one has words on the side. Patented 1819. I'd like to send you photos and your get help in identifying them.
Thanks Harrison Fried
   Harrison Fried - Sunday, 06/24/12 10:59:43 EDT

Harrison, sent mail.
   - guru - Sunday, 06/24/12 23:00:24 EDT

Tyler; I need to buy another vehicle---what's the best one for me?

Kind of hard to answer that question not knowing if I need a high MPG commuter car or a dump truck or a 4X4 isn't it.

Same thing with making a good forge: it can be one soft firebrick or one that RR cars can travel through! Knowing what you want to do with it, what skills you have---can you weld? and what equipment you have access to helps a lot.

Thomas
   Thomas P - Monday, 06/25/12 13:14:14 EDT

Old "anvils" :
Harrison's Civil War "anvils" were actually the bodies of multi-tools or vises and the patent date was actually 1914. . .
   - guru - Tuesday, 06/26/12 12:42:39 EDT

Russian Civil War, I guess.
   Mike BR - Tuesday, 06/26/12 18:56:01 EDT

There's always a revolution somewhere with civil unrest...
   - Nippulini - Wednesday, 06/27/12 12:21:49 EDT

TGN We do our best!

The Minions of Entropy---in the long run; we're on the winning side!
   Thomas P - Thursday, 06/28/12 12:25:03 EDT

Minions of entropy : The true minions of Entrppy are those of the human race of 4 years and less age. Perfect example of entrophy: Place 3 3 year olds in a clean organized room by themselves. Observe true entropy in action.
:)
   ptree - Thursday, 06/28/12 15:17:16 EDT

I have a couple of 4 legged minions of entropy too; put them and the 3 year olds together and entropy increases massively fast!
   Thomas P - Thursday, 06/28/12 16:21:08 EDT

Coal Fire wetting : I was told by a smith 35 years in the making to put fine wet coal into my buffalo fire pot with a 4X4 in the middle to make a tube. Pull out the board and get the fire going and keep sprinkling the outer area with water. Would I feed more of the fine ground coal into the fire or just toss some chunks in? I see most everyone just dumps a bunch of coal into the pan and gets the middle going. He never did that though.
   Randall - Thursday, 06/28/12 22:48:18 EDT

Randall, That is a method for using fines. Smiths who use fines generally use nothing but. Coal is fed in from the outside of the fire no matter what type. But fines need to melt and form larger chunks so they don't fall down the ash dump. Larger coal does the same but there is less need for it. But it helps when stoker or pea coal coalesces into larger pieces before it starts to coke down.

Fire maintenance also depends on the forge type and the smith's style of working. When using a bellows I used a beehive (welding) fire as much as possible due to the loss of heat while not pumping the bellows. In the same forge with an electric blower an open fire would be used more.
   - guru - Thursday, 06/28/12 23:35:34 EDT

Project Input :
We are getting ready to build a 2x72 KMG style belt grinder with the common replaceable tooling (two wheel with tilting platen, contact wheel, small wheel attachment). Since we have little need for a large diameter contact wheel that will just be a "future" option.

Having more time than money I plan to make the wheels.

My question is about wheel materials. We can make them from steel, aluminum or even plastic (nylon, delrin). While it is a little more expensive I am leaning toward aluminum due to machineability. Some folks claim you want steel for durability.

I am planning on using 5/8" ID ball bearings in 2 OD wheels. Belt speed 2830 FPM, which means about 5400 RPM on the 2" wheels. I've got shielded bearings but sealed is an option.

Anyone with experience between shielded vs. sealed bearings on a belt grinder?

One difference between shielded and sealed bearings is about a 40% reduction in speed rating for the seals. . . For a higher speed rating in a sealed bearing they must be stainless, which cost about 4 times that of steel bearings but have much higher speed ratings. If we want to run the grinder faster using a backshaft then we have to go with the higher priced bearings.

Bearing ratings are based on an 800 hour life at a given load/speed. For a machine like a grinder that is a lot of hours. If you ran it 8 hours a day it would last 100 days. But operating hours are usually much less. 4 hours would 200 days, 2 hours 400 days (18 moths of working days). That is pretty high usage. If the bearings are rated for double the load/speed then the life of the device is more than doubled. Over speeding greatly reduces the life as does dirt/grit.
   - guru - Thursday, 06/28/12 23:37:09 EDT

Mike T. : Guru, From what you have said,I would go with the sealed stainless steel bearings, I believe it would be paramount to keep out grit at higher speeds.
   Bearings - Friday, 06/29/12 02:11:54 EDT

Bearings : I'd probably try to go with 3/4" bearings and definitely use the sealed ones. If you go with double-row bearings you drop the individual ball/race loadings and can cheat a bit on speed. I'd use aluminum for the wheels, though steel is better. All that said, I'd buy my wheels from Sunray - their prices are good and if you tell them what you're going to be doing with them, they'll supply you with the proper bearings at a better price than you can buy them singly.
   Rich Waugh - Friday, 06/29/12 04:39:17 EDT

Wheels/bearings : Jock, some of the lower priced industrial belt grinders use plastic idler wheels, but they are usually in the 3-4" od, and are covered so never as a contact wheel. I would go with aluminum for the low starting inertia, and ease in machining and also in taking a skim cut when they wear.
Consider the belt sander to be much like a Little Giant in that the actual use of the machine is detrimental to the machine, IE as soon as you start using it, it starts to wear, since grit(scale) and heat are the enemies of bearing surfaces. In my industrial experience, bearings last longer than the contact wheels and platens, since the good cloth belts are also pretty abrasive on the back sides and pick up grit instantly.
I think sheilded bearing, and make them easy to change.
   ptree - Friday, 06/29/12 07:16:18 EDT

Bearings :
The bearing size I have picked is 5/8" ID and 1-3/8" OD. The 3/4" ID would only leave a 3/16" wall in 2" wheels. I'd have to use larger wheels to prevent distortion in aluminum. While the load capacity goes up, the RPM rating goes down with larger bearings. Since the load on the machine is a small fraction of the bearing load I'm not sure there is any advantage.

3/4" OD bearings only take a 1/4" shaft which I think is too small for overhung loads. I'm using 5/8" shoulder bolts for shafts. These are high strength and have a 1/2" threaded end which is pretty stout. The Beaumont KMG grinder uses 1/2" ID bearings but I liked the 5/8".

I had considered the starting inertia since the drive pulley is pretty good diameter. Of course this can be reduced by machining out all extra material. . . time consuming and costly.

I just looked at the Beaumont Metalworks page and their wheel prices are not bad. I could not buy the metal for what the large 6" wheel sells for. But I will probably still make my small wheels.
   - guru - Friday, 06/29/12 12:07:47 EDT

Platens : Platen wear can be reduced by making it from a piece of stainless. This is much more abrasion resistant than carbon steel and since it is always bare would prevent rust. My Milwaukee belt sander (yes a different animal) has a .010 stainless sheet over a thin layer of foam rubber. The trailing edge is showing wear but that is all. I've sanded as much metal as wood with this tool.
   - guru - Friday, 06/29/12 12:16:43 EDT

Belt Sander wheels : Jock, I too was a little surprised that you are going to make your own wheels and commercially manufactured ones are available has so many times in the past you have recommended that others would find it difficult to economically manufacture something which has the benefit of mass production. One error in the turning process can waste a lot of time plus the material.
   - Chris E - Friday, 06/29/12 12:25:33 EDT

More Bearings : If bearings need more protection then the wheels could have secondary shields made into them. A thin cover with a close fit to the shaft and bolt head. A lot of work. The closest thing I see to this is on some contact wheels that have a cover over the outboard side bearing.

Changing bearings in these wheels should not be a problem unless the press fit is too tight. I made sure the high priced stainless bearings were available in the same size as the ABEC-1 precision steel.

WEATHER: The temperature here is officially 95°F and supposed to reach 102 to 106°F. But our indoor-outdoor thermometer is saying well over 110. . . so we moved it. Its hotter in the shop than out in the yard. Any way you look at it, ITS HOT!
   - guru - Friday, 06/29/12 12:44:41 EDT

Randall : Joe Pehoski showed me the 4x4, wood removal fire years ago. I tried it for a while, but eventually the nice central fire gave way to coke forming and a bit of collapse. It finally turned into a regular coke fire like I normally built in the past. Wet coal can be coned up around any coking grade fire as you work. As with any fire, dry or wet, you feed it from the inside out. Formed coke is pulled in from near the hot spot, and green coal is pulled and pushed in behind it and around it.

There might be some confusion about the term "fine" or "fines." To me, fines are sand and powder size. Fine, wet coal could mean pea sized. With either, the wet coal will pack around the fire steeper than the angle of repose.

Wet coal is useful for building a trenchy, long fire, which is needed on occasion.
   Frank Turley - Friday, 06/29/12 12:53:28 EDT

Making Wheels : There is a machine shop where I live. I was in there one day talking to them about making something for me from drawings. He said give me some time to study your drawings and measurements and I will call you with an estimate. I was amazed at the equipment they had, I am not an expert on the cost of the machines, but I would guess several million. I would make drawings of the wheels with specs and take them to the local machine shop for an estimate. It might surprise you at how cheaply they would do it. I know they make their bread and butter from doing work for industries and factories, but for a good old boy needing a little help, I was surprised at how they take an interest.
   Bearings - Friday, 06/29/12 14:26:28 EDT

Bearings : I had bearings on the brain....Ha Ha
Mike T.
   Mike T. - Friday, 06/29/12 16:21:55 EDT

I have been toying with the idea of using B tank Turbo torches (in a dual burner setup) in place of my current MAPP Bernz-O-Matic TZ-8000 torch in my forge. While the idea of running a manifold off a single B tank with two (or more) turbo torch heads sounds nice, the 1/7th rule is too probable as the B tank is an air/acetylene kit. I can get the B tanks (filled) under $30 each. The torch/regulator kit runs about $100 average per torch. Any thoughts/tips as certain Turbo torches are not adjustable, I like being able to tune the forge down when not in use.

BTW, I have absolutely no experience with coal or coal forges. Come on people, it's the 21st century! Heh heh
   - Nippulini - Friday, 06/29/12 16:29:49 EDT

Nip, Are you talking about running an acetylene forge? If so its MUCH TO hot. For the same price to fill you can get 4 to 5 times the fuel in plain old propane. Put dual or triple propane torches on that min-forge.
   - guru - Friday, 06/29/12 20:12:21 EDT

Clay a Brake Drum Forge? : Hello, I've got all the parts together to make a brake drum forge, and now I'm contemplating lining the fire pot with refractory cement. Partly to extend the life of the forge and to give the fire pot rounded bowel like sides (similar to the shape of the forges in a shop that I had been renting space at) as opposed to the straight sides it has now.

From what I understand the rounded shape would make a better coal bed and reduce fuel consumption, unfortunately what I have right now is a lot of theory with a little practice.

So I ask some experts, would it be worth it to use refractory cement to round out the brake drum fire pot?
   - Bob - Friday, 06/29/12 22:43:36 EDT

Bob, Most brake drum forges are a little shallow to be clayed and don't really need it. Due to the small size you need the volume for fuel. If the drum is a fire pot built into a forge table where you have a coal reserve then claying to shape would be beneficial.

A good fire pot shape helps focus the heat in a small deep fire and reduces spreading into the coal reserve.

Refractory cement can be used but is overkill in a hobby/experimental forge. Plain clay OR plain clay with a little portland cement will work.

A small forge is handy but a brake drum forge is a beginner's forge and good for testing coal (before you buy a ton). As a DIY project from junk it is best not to invest a lot into one.

Other items can make firepots as well and perhaps better. Small old cast iron sinks are a better pot shape but many are too large. Some auto wheels are a better shape than the brake drum if you cover a few holes. In Alan Rogers Forge and Anvil series he built a forge from a wheel barrow pan and dirt using a tweer much like in our brake drum forge plans. This provided room for a dirt fire pot and fuel reserve.

Have fun, don't take it too seriously.
   - guru - Saturday, 06/30/12 00:16:12 EDT

Grinder wheels : I have one of the original Clontz grinders. Ray used 6" rubber covered aluminum industrial cart wheels for the drive/contact wheel, and a solid aluminum block turned to a crowned wheel, counterbored to accept common auto wheel bearings as the adjuster. When the bearings wear out, you just run to the nearest parts place, or keep some extras on hand. (Like I will remember where I put them.)
   John McPherson - Saturday, 06/30/12 07:27:23 EDT

Bearings and Bearings :
There are many types of auto wheel bearings. On older cars most front bearings are Timken tapered roller bearings. These are some of the best bearings ever designed but they require separate seals and either shims or an adjustment system to hold things together. Timkens were used because they take both high axial as well as radial load. Sloppy mechanics often replace the central cone because it is easy and just falls out but the pressed in out cup should always be replaced at the same time. I'm not sure what they use on front wheel drive cars today but I am sure they are too large for building a grinder.

Rear axel bearings are generally sealed ball bearings but older cars often had unsealed bearings that were lubricated by the real axel gear oil. In most cases these are too large for building a grinder.

There are many other places that ball bearings are used in autos. The most common is in alternators, power steering, water and AC pumps.

Then there are lots of other bearings, angular contact ball, needle roller, roller, spherical (self aligning) roller, spherical race ball, spherical housing (self aligning) pillow block bearings and many with flanges, snap ring grooves and other features.

The two most common series of ball bearings are Inch and Metric in standard and high precision and then open, shielded and sealed. Higher precision bearings have higher speed ratings. Designing around almost any standard inch or metric bearing assures easy replacement.

One of the easiest ways to use ball bearings is with shouldered or snap ring type. Then a straight bore is used and the bearings shoulder on the end of the bore. These are not to be confused with cheap low precision conveyor bearings. They are also hard to find in many cases.
To use non-shouldering bearings the bore needs shoulders to position the bearing.

Study catalogs and catalogs and catalogs. . ..

I've speced bearings for a lot of typical machinery applications (moderate speeds, clean conditions) but not for high speeds pushing the bearings in a dirty environment.
   - guru - Saturday, 06/30/12 11:22:10 EDT

Bearded Axe : What techniques are used to create the beard part of a bearded axe? I am having trouble drawing the metal own in that shape. Thanks,
   - Eric - Saturday, 06/30/12 15:04:39 EDT

bearded axes and contact wheels : Eric: Two ways:

1. Start with a rectangular block of steel something like 1/2" thick x 3 inches wide x 6" long, forge down the eye end, and spread the blade end with a crosspein.

2. Make a regular axehead out of mild steel, then slit the edge end and weld in a large chunk of blade steel, dress the welds while forging to shape.

There is a gentleman out in San Jose named Jim Austen who has perfected a few ways of making Viking axes. Look him up!

Contact wheels: I just bought a 4" and 6" from Sunray for less than a single 6" from Beaumont. Steel core with about 3/8" thick urethane coating. The 6" has a little vibration. I also specified 70 durometer, should have spec'd 80. They're a little soft. I'm also not sure about the longevity of the Chinese sealed bearings. I should have just gotten the 6" from Rob at Beaumont, he's a great guy and uses the best materials, properly balanced and everything. Speaking of bearings and Beaumont, they use 1/2" shafts on the KMG grinder, and mine have been working with no problem for nigh on ten years now.

I also use a ceramic platen liner. They wear better than most steels, and are easy to replace. Just don't smack one with a big chunk of steel!
   Alan-L - Saturday, 06/30/12 15:43:30 EDT

edit on axes : D'oh! My bad, Jim is in Oakland, not San Jose.
   Alan-L - Saturday, 06/30/12 15:44:18 EDT

Grinders : Bearing were single row sealed for the aluminum idler. I would check with Lowes or Home depot as they stock some sizes- list them as pump bearings, Just in case you have one go out on a week end. I have had good luck with the Chinese bearing I get off Ebay(cheap). My early grinders used a Bassick caster for the contact wheel. The urethane(rubber) was machinable so I was able to machine the OD flat. On the idlers, I machine a 1/2 to 1 degree taper from each side to form a center crown for belt tracking. After many years of use, the crown will wear down on the aluminum wheel- about 2 layers of 3/4 wide masking tape on the center will work for years as the crown- on 2 inch wide or wider belts. I have used this trick on my 6" x 48" belt grinders- works great
   - Ray Clontz - Saturday, 06/30/12 17:07:27 EDT

Bearings and Shafts : One advantage to making all my own idler and tracking wheels is that I am going to use the same bearings in all of them and will have a few spares. The exception would be small diameter contact rollers and they would use a smaller bearing (more spares).

I'm buying my bearings from McMaster-Carr. The prices are not the cheapest but I know what I am getting. Standard and precision ABEC-1 bearings look just alike but the precision bearings have a higher rating thus a longer life. They also list the pricey much higher rated stainless bearings in the same sizes.

The first batch I bought were made by Koyo of Japan. But you never know where things will be sourced from when buying from McMaster-Carr. However, in the bearing business they come from all over and I have bought 4 or 6 bearings from a power transmission outfit and gotten more than one manufacturer in the batch. . .

Going with the slightly larger bearings has pros and cons. The smaller 1/2" bearings use a lighter shaft which I did not like for an overhung application. However, they have a higher RPM rating. I am using precision shoulder bolts and they have a significantly smaller threaded section (1/2" on 5/8"). If I used 1/2" the threaded part would only be 3/8". So I lose a little on the speed rating and gain a lot of strength on the shaft.

I like the larger shaft because I've seen too many pieces snag on various grinders and buffers resulting in bent shafts. It may be overkill but that is the direction I am going.

The shoulder bolts as shafts have a lot of advantages. They are easy to source, they are made from hard heat treated material, they are precision and made to common standards. Designing around these results not needing to make shafts or to modify other fasteners to make shafts. They are not inexpensive but they are much less costly than having to machine anything yourself AND they are easy to source replacements.


   - guru - Saturday, 06/30/12 20:25:44 EDT

4 wheel Grinder Question :
The one thing I am not clear on at this point is which wheels are crowned and which are not.

I know the drive wheel (if its not a contact wheel) is crowned and so is the tracking idler.

I know contact wheels are not, but what about the 2" or so wheels on the double wheel platen?

   - guru - Saturday, 06/30/12 20:32:31 EDT

Tomahawk Handles : I am making a railroad spike tomahawk from Bill Epps'how-to. My question is- what diameter whole is required for a sturdy enough handle. Since the handle slips down from the top of the axe the entire length must be the same size as the hole. I am worried mine is too small and thus my handle will break when it hits something if I miss my target. My hole is 3/4 of an inch in diameter. My handle is made of ash. Do you think this is large enough, or do I need a larger hole diameter? Is there a standard on this sort of thing? Thanks so much in advance,
   - Eric - Saturday, 06/30/12 21:33:42 EDT

4 Wheel Grinders : Mine just has a crown on the idler wheel. I suppose there wouldn't be harm in having the drive wheel crowned but mine doesn't seem to suffer any tracking issues without it.
   - Martin - Saturday, 06/30/12 21:44:46 EDT

Tomahawk Handles : Eric, I'm not a blade smith nor am I a blacksmith. I am an artist and millwright by trade. However, I own a tomahawk. I know how to throw one and I use mine to chop and shape wood on a regular basis. The hole or eye of your tomahawk should not be round. It should be oval or teardrop shaped so that the handle does not spin when you strike a surface. A 3/4 inch hole seems very small for such a tool. There are a number of ways to resize the hole but it will depend on how much material makes up the side walls and what tools you have available. The guru and several others on this site will have better and more in depth information on doing that than what I can provide.

The handle itself should be tapered. Mine goes from one and a half inches at the top where it seats in the head, down to about an inch at the bottom of the grip. It also changes shape as it transitions. The top is a very distinct teardrop cross section while the bottom is simply oval. With this shape and these dimensions the head stays firmly in place while in use but if you throw it and the handle strikes first the head will often jar loose and slide down the handle causing less damage. I've had my tomahawk since about 1995 and have used it to chop wood very often since then. I have only had to make seven new handles in all that time. Only five of the handles actually broke from use. Two wore out and were "retired" to other tools after I reshaped them.
   - Bill - Saturday, 06/30/12 22:20:11 EDT

Handle : Thanks, thats extremely helpful!
   - Eric - Saturday, 06/30/12 22:35:34 EDT

Eric : you can get an idea of shape and size from www.crazycrow.com catalog, hawk handles. Most of the eyes that are shown look like a combo of a teardrop and an egg shape. Some pipe tomahawks had a lozenge shaped eye with radiused corners.
   Frank Turley - Saturday, 06/30/12 22:49:44 EDT

Tomahawk Handles :
Eric, Bill's spike axe is a small one but the eye needs to be drifted out larger than 3/4" round. These handles are tear drop shaped with the length about 1.5 to 2 times the width. The demo shows the shape.

There is a standard used for heavier tools that starts at 2 x 3" (Eye No.8) and a 1-7/8 x 2-1/2" (Eye No.9). I've found no standard for throwing axes but the commercial drifts are these proportions.

To make the correct hole you slit with a straight edge chisel then open the hole. Then you drift with the tear shaped drift making the hole round at the back and pointed at the front.

I suggest you purchase handles and drifts from Blacksmiths Depot OR a handle and make your own drift to fit the shape.

To make this shape drift you make the tapered round first, then slightly oval. Then working with the drift parallel to the edge of the anvil work at an angle to draw out the pointed edge. Its a lot of work to get the finished shape and you may want to just rough it out then grind to final shape. To meet standards the hard part is the front to back taper is 4° per side (8° included) and side to side is 3° per side (6° included).
   - guru - Saturday, 06/30/12 23:08:55 EDT

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