Adding A Column Riser To A Solid Column Mini-mill: Lots Of Questions

"I'm thinking I'll put both in and leave it like that unless the hit to rigidity is too serious. I'm sure I can borrow a torque wrench from the maintenance shop"

...and Elizabethtown, Kentucky. Are you at Fort Knox?
 
One may also clamp a flat piece to the table by drilling, counterboring and clamping it down with socket head cap screws and T-slot nuts, then skim the surface, drill and tap and then screw your part down. It does not need to be any bigger then the part itself, if you have the Z clearance to do it in a vice then there is certainly room to do it screwed to a sub 1" high fixture on the table.
This sort of simple flat fixture may be reused many times, simply bolt it down to the table and skim it again, drill and tap new holes for the new part and have at it.
Good Luck with your project.

If one is overly concerned about accurately "tensioning" threaded fasteners a torque wrench is about the least accurate method (aside from a large handheld non-torque wrench) yet the only method available for general work.
For those hobbyists suffering from crippling OCD about accuracy , Rotabolt as well as several other manufacturers such as Maxbolt™ make exactly what you seek. However you will not be at all happy with the cost.
http://www.rotabolt.co.uk/how-it-works/
Maxbolt https://www.vfbolts.com/product/maxbolt-load-indicating-fastener-system/

That would work pretty well actually. I've got a big plate of 5/8" 6061 and some short SHCS I could use as a base. Thanks! Now my only real worry is getting under the skin of the casting without carbide tooling. As for the torque, I don't plan on being super anal about it, I just want to really crank them down without stripping the threads out of the base.


"I'm thinking I'll put both in and leave it like that unless the hit to rigidity is too serious. I'm sure I can borrow a torque wrench from the maintenance shop"

...and Elizabethtown, Kentucky. Are you at Fort Knox?

Nope, I do R&D at a plastics company in E-town itself.
 
That would work pretty well actually. I've got a big plate of 5/8" 6061 and some short SHCS I could use as a base. Thanks! Now my only real worry is getting under the skin of the casting without carbide tooling.

There is no reason that the CI will have a hard surface unless done intentionally.
 
There is no reason that the CI will have a hard surface unless done intentionally.
Really? Just about everything else I've read has said that raw gray iron castings have a hard "skin" where the molten metal quickly solidifies as it touches the cold mold and that getting underneath that can be a bear.
 
Haven't had a problem with HSS. Just don't try to take a 5 thou first cut.
 
I got almost another 2" I think it is out of just changing the gas strut to one off an old Riviera. I also made a new stop to go with it. I have not been looking for any more height since making this mod. It's more than enough room to change out tooling, if you keep the projects proportional to the size of the equipment that your using. I also made a stiffener for the column at the same time because mine is not the solid mounted type. In my pics, I show how I did it along with the part numbers and plans, along with a whole host of other mods I've made to my mini mill.

http://www.hobby-machinist.com/threads/my-lms-mini-mill.22202/
 
I'm looking at adding a spacer to my Clausing and came across some threads suggesting MIC-6 Aluminum plate.
It's made for jigs and comes already pretty flat. Seems to come in thicknesses up to 4". Offcuts are cheap on eBay.
FWIW, I'd also think about making your part L shaped so it comes down over the rear of the base. You could add a couple of bolts there to resist some of the flexing force.
 
Really? Just about everything else I've read has said that raw gray iron castings have a hard "skin" where the molten metal quickly solidifies as it touches the cold mold and that getting underneath that can be a bear.
The molds are sand which is an excellent thermal insulator, some molds have "chills" incorporated into them in order to achieve different characteristics in specific locations on the same casting. A cast iron stock product, round bar and tube, rectangular bars etc. intended for later over all machining would not benefit from such a practice, if one day you come across a casting that that has an intentionally chilled area you will know.
I turned a piece of 2 1/2" round CI stock from McMaster yesterday, the surface was no harder then the rest, on a complex casting you may encounter sand inclusions which are an entirely different animal.
 
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I got the CI bar yesterday and took it to the makerspace. Unfortunately the vice they have on the bridgeport is absolute GARBAGE. I tried to use the brazed carbide bit I had that bought for my current fly cutter but halfway through the cut the casting started moving around and the bit got trashed. So I went to plan B and made a new fly cutter that would fit on the threaded arbor for my boring head using some 2.5" 7075 round bar and a 7/8-20 tap. The new head can take a bigger tool bit that has carbide inserts so I have more than one try if I mess up.

I finished the fly cutter head this morning at work and tried fly cutting the CI smooth on my mini-mill and it worked great. I had to walk the fine line between getting under the skin and not bogging down the spindle with the small motor buy I only stalled out once. Hopefully once it's all squared up the rest of the project (drilling holes and mounting the column) will go fairly smoothly.
 
Please take & post pix during this mod. Very interested in seeing the results.


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