BobL

Iron ores that contain sulphur have to be combined with manganese in the blast furnace or the hot iron becomes "hot short". The WIkipedia entry on iron ore has a section on the significance of sulfur in ores and the coals used in blast furnaces - it's right at the bottom of the article. It also has some references to blacksmithing.

There are "nanotubes" and "carbon nanotubes" The Wikipedia entry for Carbon nanotubes (http://en.wikipedia.org/wiki/Carbon_nanotube) is pretty comprehensive. Read the potential applications and you will see why they are a hot topic.

It does sounds like you have confused the insulation used for cheap "metal casting" with the insulation needed for a forge. Depending on how it is made and what is in the sand, a sand/plaster of paris mix is likely to have high conductivity at low temperatures (so anything insulated by it will take a long time to heat up) and while it may even have a moderate to low conductivity at higher temperatures, it won't stand up to repeated heating that happens in a forge.

I agree, If there is one thing schools and parents could teach, value, and place and increased emphasis on, it's how to ask the right questions. Far too much time is spent on chasing answers to trivial questions that requires little mental processing and can be looked up in a book or on the net. Asking a meaningful question is often harder than finding an answer. When I was a college instructor I occasionally used to set components of assignments where the student had to construct a problem that had context, depth and a non-trivial answer that they could solve. The students hated these because they had to spend a lot of time thinking and answering them. I got this idea from one of my old college professor who said "success in life is not about finding the right answers but asking the right questions"

Correct. It's a real challenge because the pressure of our gas supply in our area is very low (0.2 psi)

I finally got my natural gas line out to my shop. The line is 72 ft long and had to go under brick paving, sewage, stormwater and mains water pipes, and 3 garden reticulation line, I also managed to hit about 6ft of old builders rubble and glass plus tree roots everywhere. Anyway it's done, and it's 3/4"diam pipe all the way from the meter box to the shed. Previously it was 3/4" then 1/2", then 3/8", back to 1/2", then down to 5/16 and then back up to 1/2" - none of which helped the gas flow. The gas pressures are very low in our suburb so it was important to use 3/4" diam pipe. While I was at it I upgraded the plumbing on the forge to be 3/4" all the way to the T- piece where it divides into two 1/2" lines to the two torches. Not much different to see. I removed the idler line as it was not working well and I need to reconfigure it. The box of electronics is a new starter from an old gas Hot water System (HWS) we had recently replaced Here is a close up of the starter It uses 2 D size 1.5V batteries. The HV unit from the HWS has a number of sensor inputs which are basically relays that can be short circuited except for one that is wired to a switch. Throwing the switch sends a fat spark across the spark unit with a frequency of about 2 sparks per second so it lights a bit more assuredly than the push button BBQ starter. Previously I was gas flow limited but that does not seem to be the case now. It's 8:30 at night here but I fired it up briefly and got to 1100ºC with just the front torch running with the valve opened about 3/4 of the way, and lots more air to play with too, so still have a lot to experiment with.

Love it!

Those magnets seem to work pretty well, but won't the whole anvil eventually become magnetised after a while? Also what's caulk, you mean like standard silicone out of a caulking gun/tube?

Those magnets seem to work pretty well, but won't the whole anvil eventually become magnetised after a while? Also what's caulk, you mean like standard silicone out of a caulking gun/tube?

Positive pressure extraction is used for areas that are already contaminated with stuff like smoke or poisonous gasses but it would be far better if a shop was never left to get that way. A much better way to go is to apply high flow negative pressure at the source. This has been well developed in wood working where the point of dust generation by machines and tools are directly attached to dust extractors. Initially developed as chip collectors the dust extractors have been extended to also capture the more health significant invisible dust (ie smaller than 10 microns) which acts more like a gas than chips. I have access to several different dust particles counters and have studied this is some detail in dozens of woodshops. Capture of invisible dust from machinery at source requires high flows (1000 cfm) but it is not impossible as it is being done regularly by many woodworkers. Whether these flow rates are what is needed to keep the levels of contaminants down in a metal shop is another matter. It depends what you are doing. If you want to trap gasses and dust at source then the more flow you can get the better. BTW the maximum a 4" duct can pull with a 2 - 4 HP motor driving a 12 to 16" impeller is about 450 cfm There are many 2 and 3HP with 12 or 13" impellers in use in woodworking that can pull 1000+ cfm through 6" ducting. In the case of the 2HP systems they usually have 4.5" intakes and 5" outlets so they need to be modified to achieve the 1000 CFM through 6" ducting. My 3HP 13" impeller system has an 8" intake and a 6" outlet so no mod is needed If you just want to vent a shop ie no ducting or are prepared to use large (1 sq ft) cross section ducting maybe square or rectangular, then something like a squirrel cage fan may be suitable. I just replaced the 350 CFM squirrel cage fan in my fume hood with a variable speed squirrel cage fan that can draw up to 2600 cfm for short periods. I cannot run it at this rate for too long as it overheats but I can run It indefinitely at 1000 cfm. At 1000 cfm it uses just over half a HP so it is very cheap to run and much quieter than a woodworking dust extractor.

http://www.liogier-france.fr/?lang=en

Either way it will look great, land I just love your shop. I showed my wife your design and she thinks two dragons as well. BTW I retired about 3 months ago and over the two years prior to that I built and setup up a small (450 sq ft) shop in our inner suburban back yard. I sort of completed it about the time I retired so right now I am having a great time.

Yeah it gets complex very quickly This is the chart I use. It shows the CFM possible for a given pressure differential along different diameter pipes. The purple shaded area shows the typical pressures possible with conventional impellers ie 6 to 20" of Water Column (WC). I modified it so that I could include vacuum cleaner type pressures 50 - 90" of water column. The red dot shows that a 6" siam duct can at most transfer 1000 cfm when the pressure differential between the ends is 6.5" of WC To generate this pressure you will need at least a 2HP motor and a 12" impeller and 6" diam or more openings all the way through the system. I have just finished testing a 2HP/12" impeller from a generic dust extractor unit that the manufacturer claimed was a 1200 CFM with 8" of WC unit, but it was in stock form <600 cfm and 7" of WC. By simple modifications I was able to make the impeller move 1100 cfm and generate 8.1" of WC. This of course is just the impeller, If significant lengths of ducting are used then the flow rates will drop off pretty quickly. To move 1000 cfm through more than say 10 ft of 6" diam ducting a 3 HP/13" impeller is needed.

This seems like another "how long is a piece of string" question. Given you don't have a welder, if you purchase all the parts new and then pay someone to fab up the necessaries, it could easily cost more than a store bought unit. However, if you are crafty and good at scavenging the parts can cost very little. I am in he middle of collecting up the pieces for a large ( 6" wide x 24") long belt sander. It will be used more for woodwork but I will also use it a lot for metal work. - 1" diam steel shafts and two of the pillow block bearings I got for nothing from a friend, the other two bearings I stripped off a machine I found in a dumpster. - aluminium drive roller/drum I had my BIL fab up for me from a 4" diam x 9" long piece of ally pipe - other rollers are scavenged at no cost from a railway line grinding machine - 2HP 3phase motor cost me $35 from the online classifieds. - motor has the right pulley on it and I bought another pulley for $10 from ebay. - frame is going to be made of 1.5" x 1/8" SHS which I have pieces left over from another project One thing I have spent serious money on is a box of electronics, a new variable speed drive (VSD) which enables the 3phase motor to run off single phase as well as providing speed control but even this cost only $120 delivered. I already have a small but handy metal shop with a small metalworking lathe, 170A welder, 4 grinders, metal cutting bandsaw, Floor standing drill press etc, so putting this together should not be too difficult. I also have access to a shop with mills and other larger metal working gear. I have experience with installing 3 VSDs. Building a belt grinder without these would be quite challenging. I hope this gives you a few ideas but hopefully someone who has more direct experience with a dedicated belt grinder for metal will respond.

I just realize my smallest chainsaw mills is set up perfectly for this sort of thing, ie make a flat cut and then make another perfectly parallel to that first one.

I made these chunky levelling feet for a metal working bench but never got around to using them so I just bolted them onto the side of my stump. The stump still sits firmly on the floo,r the feet just help stabilize it and remove that last little tiny irritating bit of rock that I just can't seem to get rid of. This will keep me going for a while but I do spend a couple of days in a tree lopers yard milling timber so I will cut myself an new and improved stump when I get around to it.

I just realized the image I thought I had posted in my previous post in this thread did not appear. Anyway, here it is. Also I show a couple of photos of my metal work fume hood. Extraction uses a variable speed fan up to about 500 cfm

RE: What is the best place to locate a clean air intake? low or high on a side of a wall? or on a roof? If you want to maximize air exchange within a shop more than one intake should be used with most of them as far away from the exhaust as possible. If they are too close to the exhaust the air will come in and go out too quickly without properly venting a shop if you want to focus on providing clean air for the operator and the operator spends most of their time in one area then the intake(s) should be such that they forms a line between the operator and the exhaust. RE; What should I weld hoods out of and how big are traditional hoods over a gasser? -and how many CFM should i be looking at to draw the bulk of those gasses off? I reckon using what you have to hand is a reasonable way to go. one of the most effective hoods I have seen on a forge was made out of kerosene cans. I used the left over mini corrugated iron cladding I used for the interior of my shop. RE: Is there anything better than dryer-type ducting at home improvement stores out of which to build a point extraction arm? Before I had my fume hood I used to vent my shop while stick welding with my $100 wood work dust extractor and 4" PVC storm water ducting. As a point extractor I used a 10 ft length of transparent PVC 4" flexy ducting suspended from a wire between two walls of my shop. The wire and flexy traversed across the top of my small metalwork bench and I could slide the flexy along the wire to get it directly above the work. At first I was very conservative as to how close I would let the end of the flex get to the work but I quickly noticed that (especially at night) the transparency of the flexy enabled me to see how far the sparks would get down the duct but in was never more than a ft at most as the rush of air seemed to cool them down rapidly.Sure the flexy got a few holes and charred marks but it worked well for 6 years and had plenty of life left. A few times I thought about including a metal chip catcher between the flexy and the dust collector (which was outside my shop) but I never bothered because my dust extractor was so weak (1HP) that a lot of metal dust never would settle out in the flexy so every few months I had to take it down and empty it out. The other thing that the welding fumes did was gum up the extractor bags so they had to be washed more often than I liked which is why I decided to make a fume hood for my new shop. You could use a combo of both the dryer metal type ducting for the first couple of ft and then PVC after that BTW most conventional dust extraction units simply cannot pull more than about 400 cfm through 4" ducting. 6" ducting can carry ~1250 cfm BUT a 3HP or greater motor and 13" or greater diam impeller is also needed. OTOH using 6" ducting on a small dust extractor will result in the dust settling out in the ducting as happened to me above There is a very instructive chart/graph around on the web that shows what CFM can flow through what diam ducting under what pressure. I have measured the flows through a lot of ducting and blowers and this chart has rarely been wrong. Anyone contemplating setting up a ducting system should really study this to see what is possible and what is not.

Now I understand the name. I just had a look at the average highs for Anchorage and the only month in the year where the average high is higher than Perth is July (66 versus 65) - don't forget that's mid-winter for us. I like winter's here - there's a bit of rain every now and then otherwise it's nice and sunny and as we call it "cool".

Most turbos output a lot of air so you will need some way to control the flow. The idea way would be to use a variable speed electric motor but the most common way to do this is with a simple spill valve. However, if the turbo is from a big engine then depending on what RPM is used you might end up with a gale coming out of the spill valve so some form of speed control will be needed. The attached graph gives you an idea of engine CFM requirements versus RPM at different engine displacements (in cubic inches) - this is not exactly the same as turbo outputs but it gives you an idea of engine requirements. For example a 350 cin engine draws about 300 cfm at 3000 rpm while a 100 cin needs about 90 cfm. My guess is you will need less than 100 cfm to run a forge so if you do decide on a turbo then one for a small engine (~100 cc or less) would be all that you would need. Whatever you use It seems like a very expensive way to go.

If you hope everything will just go up to the top of the inverted V then you will be disappointed as the "stuff" will diffuse all over your shop about as quickly as it rises. You may not even see what the stuff is as most of it is invisible to the naked eye but it will be there and heaps of it. Hoods and exhaust conduit create a much higher air speed with a specific direction than simple bulk rising thermals. The faster the air stream the more it can carry before the heavier gunk has time to settles out. I'm not talking metal chips here but pretty well everything I have a 500 cfm fume hood under which I try to do as much metal work as possible. This helps reduce the level of grey goo that normally settles all over my small shop during metal working. I'm lucky enough to have a laser particle counter so I can routinely test my shop air. I normally use this for wood dust assessments in hobby type wood workshops but I have used it to test my shop air during metal working and it gets pretty bad unless I have my fume hood operating. I also have a fully ducted 1250 cfm wood dust extractor system that also extracts to outside my shop (it rarely gets cold but I do lose my air conditioned cold air in summer) but I don't use this for metal work as it will block my wood dust extractor filters with "grey metal goo". BTW I also have flow testing gear and have tested the flow rates of a range of dust extractors and fans and the manufacturers ratings are almost all incorrect by at least a factor of two (2 times higher than they really are) and by the time ducting and filters are added it can be more than a factor of 6.

What's the story behind these tools?

Onya Lance. Lookin forward to see what you get up to. I'm still in the middle of a kitchen reno - as soon as that is done I will extend the gas line down to my shed so I can get back to the forge. Bob

I haven't treated a screwdriver since high school metal shop nearly 50 years ago but I still have the screwdriver I made and it has worked well. Standard harden and temper to dark straw was the method we were taught. I have tempered a fair bit of stuff since then - I use our kitchen oven as it is accurate all the way up to the max temp of 250ºC.

RE" "how can I get the most spring into it? I want it to be able to bend and return to the original shape with out it breaking or loosing the shape I forged it into" What your specification lacks is 1) how far you expect it to move and 2) what sort of force you are going to apply (or) the return force you are looking for. The ratio of these two are related in a quantity called Elasticity or Young's Modulus and is the standard measure of the "springiness "of a material. All solid materials have "spring" over a certain distance range but beyond that distance (called the elastic limit) they deform and remain deformed, more bending and they break. For mild steel the distance range over which it remains elastic is limited, and as others have said heat treatment changes nothing. Perhaps counter counter intuitively, spring steel has an almost identical elasticity to mild steel, but spring steel be heat treated to increase the distance range over which it remains elastic. If spring steel is bent beyond its elastic limit it too will stay bent. In other words, heat treatment of a specific piece of spring will not change the return force available for a given deformation but it will change the distance over which it can be bent and still return to its original shape. Obviously if the object can be deformed over a greater distance it can return a greater force, otherwise the way to change the return force is to change the shape of the object. The other way of course is to change the material. There is a good discussion here about this. http://bbs.homeshopmachinist.net/threads/29279-Modulus-of-elasticity-changes-due-to-heat-treatment-of-metals