Rookie Question
- Thread starter Gary
- Start date
KeithB
Resident Half Fast Machinist
I would give it a qualified maybe. I'm not sure what the requirements are for the parts in a GC maker. It is hard to determine exactly what material a bolt is made of. Most bolts are specified by performance/strength and so the materials that make up a bolt may vary as long as the performance standards are met. If you have to heat treat any of the parts not knowing the material composition can be a real problem. If you are just going to use the material as is then that isn't a big issue. If you do have to harden a part to use it as a shear or punch then I would recommend using O1 (oil hardening) or A2 (air hardening) tool steel or 4140 alloy steel. All three can be heat treated using simple methods to make a part hard enough to shear brass and aluminum easily and hold up well.
Don't let anything I've said keep you from trying what you've got, it may be just the ticket. My views are colored slightly because I have access to a lot of materials of known composition. If you need something specific feel free to message me, I may have something you could use.
Don't let anything I've said keep you from trying what you've got, it may be just the ticket. My views are colored slightly because I have access to a lot of materials of known composition. If you need something specific feel free to message me, I may have something you could use.
KeithB
Resident Half Fast Machinist
Which just about screams for heat-treated O1, A2, or 4140. I've made form tools to cut plastic, brass and aluminum from all three materials. Not as good as true High Speed Steel but at slow speeds (to prevent heat softening) it will work fine. I don't see heat issues with a hand powered check maker.
Gary
SE Kansas
This is the threaded rod I was referencing: https://www.amazon.com/Small-Parts-...pID=317TvCoRdxL&preST=_SX342_QL70_&dpSrc=srch
Gary
SE Kansas
Brad, I got the plans off CB site from 2013.
http://castboolits.gunloads.com/showthread.php?200965-Easy-to-build-gas-checkmaker
http://castboolits.gunloads.com/showthread.php?200965-Easy-to-build-gas-checkmaker
Pistolero
Well-Known Member
I would make it out of 4140 and heat red hot, drop into a can of oil. Then polish off
a portion with fine sandpaper to a shiny, bare metal finish. Then VERY gently, wave a
propane flame over it, 1 sec on, then off and watch that shiny area. One second of the
cooler portion of the flame then off to look for color. Keep doing this until it just gets a yellow
(straw) color, where the tempering starts. A bit hotter gets to brown, and just shading to
purple will take out most of the brittleness while retaining most of the hardness that
you got when you quenched from red hot. If you want softer, warm more past the purple
until it starts to go a darker blue. if you want harder just get it to straw or brown color, which is
just about minimal tempering. Yellow, brown, purple, the dk blue these are the tempering
colors in order.
Less tempering = max hardness, max brittleness. As your temper temperature
goes higher, the brittleness goes away, at the cost of a small bit of the hardness. Stay at purple
or blue and you will still have a good hard part, but it won't want to shatter like glass or chip.
Bill
a portion with fine sandpaper to a shiny, bare metal finish. Then VERY gently, wave a
propane flame over it, 1 sec on, then off and watch that shiny area. One second of the
cooler portion of the flame then off to look for color. Keep doing this until it just gets a yellow
(straw) color, where the tempering starts. A bit hotter gets to brown, and just shading to
purple will take out most of the brittleness while retaining most of the hardness that
you got when you quenched from red hot. If you want softer, warm more past the purple
until it starts to go a darker blue. if you want harder just get it to straw or brown color, which is
just about minimal tempering. Yellow, brown, purple, the dk blue these are the tempering
colors in order.
Less tempering = max hardness, max brittleness. As your temper temperature
goes higher, the brittleness goes away, at the cost of a small bit of the hardness. Stay at purple
or blue and you will still have a good hard part, but it won't want to shatter like glass or chip.
Bill
KeithB
Resident Half Fast Machinist
If you heat it up until a magnet no longer sticks to it you will have set up conditions for a successful HT job. Agree with everything Bill says. But you have to heat it and hold it long enough for a phase change to occur, and that phase change causes steel to lose its magnetic attraction. Then quench.
KeithB
Resident Half Fast Machinist
You are probably only going to have a choice of 3 or 4 commercially available alloys in SS. 304 and 316 are what is known as austenitic alloys. The microstructure is such that (a) they can't be hardened by heat treating, (b) they are nonmagnetic, and (c) they will work harden under pressure. 440A, 440B, and 440C are martensitic steels which are (a) hardenable by heat treating, (b) are magnetic, and (c) can't be welded by any common process. The can be made very hard and are often used for cutting purposes (knife blades, etc.)
The 440 series would seem to be the best choice if you're limiting your choices to SS. But in all honesty it is IMHO not a very good choice for several reasons.
1. SS machines like a pig. If you use dull tools or don't keep a positive feed the tool pressure will harden the surface to the point that it can be become virtually unmachinable.
2. Under the best conditions the machinability rating is about 50% or less of carbon steels. Plan on taking a long time to machine your parts.
3. The force required to machine SS even with sharp positive rake tools is significant, which means lighter cuts and more stress on everything. On small machines with limited power threading of coarse threads may take too much force, may not even be possible.
(A shop teacher friend of mine related how the shop he was working for bought a new top quality American made lathe in the Spring; he ran nothing but SS parts on it during his summer employment. By the time he returned to the classroom that Fall they had to replace the spindle and feed screw bearings. He wore them out cutting SS.)
We make parts from all sorts of materials and stainless steel is at the very bottom of our "fun to cut" list. It's hard on tools, hard on equipment, causes a higher scrap rate and is generally just a pain in the digestive tract to deal with.
Would SS work for your check maker? Yes, but IMHO there are far better materials available that will do as good or better job, are easily available in many shapes and sizes, machine a lot easier, and are easier to heat treat.
But I said this in an earlier post - don't let my opinion stop you from trying out your ideas and keep you from using what you can get. I base my opinions on my personal experiences, and I've made a lot of mistakes. I try to get as many things going my way as possible to make up for my limited skills. So my choices may not line up with anyone else's.
The 440 series would seem to be the best choice if you're limiting your choices to SS. But in all honesty it is IMHO not a very good choice for several reasons.
1. SS machines like a pig. If you use dull tools or don't keep a positive feed the tool pressure will harden the surface to the point that it can be become virtually unmachinable.
2. Under the best conditions the machinability rating is about 50% or less of carbon steels. Plan on taking a long time to machine your parts.
3. The force required to machine SS even with sharp positive rake tools is significant, which means lighter cuts and more stress on everything. On small machines with limited power threading of coarse threads may take too much force, may not even be possible.
(A shop teacher friend of mine related how the shop he was working for bought a new top quality American made lathe in the Spring; he ran nothing but SS parts on it during his summer employment. By the time he returned to the classroom that Fall they had to replace the spindle and feed screw bearings. He wore them out cutting SS.)
We make parts from all sorts of materials and stainless steel is at the very bottom of our "fun to cut" list. It's hard on tools, hard on equipment, causes a higher scrap rate and is generally just a pain in the digestive tract to deal with.
Would SS work for your check maker? Yes, but IMHO there are far better materials available that will do as good or better job, are easily available in many shapes and sizes, machine a lot easier, and are easier to heat treat.
But I said this in an earlier post - don't let my opinion stop you from trying out your ideas and keep you from using what you can get. I base my opinions on my personal experiences, and I've made a lot of mistakes. I try to get as many things going my way as possible to make up for my limited skills. So my choices may not line up with anyone else's.
KeithB
Resident Half Fast Machinist
Could the punch be modified into a two piece system with a 7/8-14 all thread body and a hardened steel insert that does the actual shearing? I have a piece of A2 rod in an off spec diameter (.643") that has plagued us ever since we bought it. It won't fit a 5/8" collet. Got about 6" of it left that you are welcome to.
Gary
SE Kansas
As a matter of fact Keith, I've downloaded a Utube video that shows a super simple method of making checks. Requires a minimum of machining skill to make (right in my wheelhouse) and looks like my next project. I've got the steel on hand to make the setup and it's just a matter of finding the shop time to get er done.
Thank you so much for the offer of material and your time, I appreciate it very much. I'll post pics of the finished product when I know it works.
Thank you so much for the offer of material and your time, I appreciate it very much. I'll post pics of the finished product when I know it works.