Foundation for 25lb little Giant
- Thread starter reevestx
- Start date
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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Knifemaker / Craftsman / Service Provider
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Here is what some folks do:
Use a concrete saw and cut a square at least 36X36" out of the slab. The hole can be larger, and/or rectangular if you want.
Dig the hole out at least 36" deep from floor level. Pack a couple inches of construction sand at the bottom of the hole and level it off. The hole should be around 34" deep now.
The best method of isolating the hammer from the floor is to build a 3/4" plywood box that is 2" smaller than the opening (34"X34"), leaving a 1" gap between it and the sides the slab. Set the box in the hole and seat it firmly on the sand in hole bottom. Add/remove sand to make the box even with floor level ( it may settle a tad when filled with concrete, but that is OK).
Put some 1" wide slats in the gap between the slab and the box as spacers (or whatever thickness fits snug). Double check that everything is even.
Pour fine sand in the gap between floor and box until the sand fills the space between the box and the hole in the ground up to floor level. Use a piece of 1X3 to ram the sand down hard as you fill the gap.
Fill the box with cheap fill sand 6" at a time and bang the box sides with a rubber mallet to settle the sand in the space around it. Pour down more fine sand in the gap as needed as you fill the box with sand. When the box is full of sand it should be even with the floor or a little below it.
Dig the sand out of the box. Don't worry about any stray sand in the bottom.
Weld 1" threaded rod ( or whatever size the mounting holes on your LG base are) to bars of iron or rebar so they stick up at the same pattern and spacing as the LG mounting bolts. Making a plywood template to match the base of the LG is a good idea. If you make a bolt pattern template, you can mount it to the ends of the threaded rods with double nuts. This will assure the spacing is correct after pouring the concrete. Weld on some rebar cross/diagonal braces so it is rigid. When sitting in the bottom of the box, the threaded rods should stick up about 8"to 10" above the floor level (enough to go through your base and the LG bottom.
Any rebar that is being added to strengthen the concrete block being poured can be wired and welded to this frame.
With the frame in place in the box, pour the concrete block and stop 2" shy of the floor level. This should take 2/3 yard of concrete for a 34X34X34 OD box of 3/4" plywood.
Pull out the spacer slats and remove some sand around the block to get the space between box and slab a few inches deeper than the slab ( 6" to 8"). A shop vacuum and thin nozzle is the simplest way to get the sand out.
Pour hot roofing tar or asphaltum in the gap between the box and slab edges. Tape off the floor 6" around the gap to keep it neat)
Make a base from 4X4 or 6X6 timbers that fists in the recess at the top of the box (this base will stick up above the floor), and bolt it together with through rods in at least 3 places. Drill the timbers so they will allow the threaded rods to go through it ( use your template). If you drill oversize holes, pour hot tar down the gap around the rods after the base is in place in the box.
Mount the LG to the base. Some folks put a sheet of hard neoprene or horse stall matting between the LG and the base.
This sounds like overkill, but the isolation box will support the LG well and keep a lot of the impact vibrations from shaking everything in the shop.
Use a concrete saw and cut a square at least 36X36" out of the slab. The hole can be larger, and/or rectangular if you want.
Dig the hole out at least 36" deep from floor level. Pack a couple inches of construction sand at the bottom of the hole and level it off. The hole should be around 34" deep now.
The best method of isolating the hammer from the floor is to build a 3/4" plywood box that is 2" smaller than the opening (34"X34"), leaving a 1" gap between it and the sides the slab. Set the box in the hole and seat it firmly on the sand in hole bottom. Add/remove sand to make the box even with floor level ( it may settle a tad when filled with concrete, but that is OK).
Put some 1" wide slats in the gap between the slab and the box as spacers (or whatever thickness fits snug). Double check that everything is even.
Pour fine sand in the gap between floor and box until the sand fills the space between the box and the hole in the ground up to floor level. Use a piece of 1X3 to ram the sand down hard as you fill the gap.
Fill the box with cheap fill sand 6" at a time and bang the box sides with a rubber mallet to settle the sand in the space around it. Pour down more fine sand in the gap as needed as you fill the box with sand. When the box is full of sand it should be even with the floor or a little below it.
Dig the sand out of the box. Don't worry about any stray sand in the bottom.
Weld 1" threaded rod ( or whatever size the mounting holes on your LG base are) to bars of iron or rebar so they stick up at the same pattern and spacing as the LG mounting bolts. Making a plywood template to match the base of the LG is a good idea. If you make a bolt pattern template, you can mount it to the ends of the threaded rods with double nuts. This will assure the spacing is correct after pouring the concrete. Weld on some rebar cross/diagonal braces so it is rigid. When sitting in the bottom of the box, the threaded rods should stick up about 8"to 10" above the floor level (enough to go through your base and the LG bottom.
Any rebar that is being added to strengthen the concrete block being poured can be wired and welded to this frame.
With the frame in place in the box, pour the concrete block and stop 2" shy of the floor level. This should take 2/3 yard of concrete for a 34X34X34 OD box of 3/4" plywood.
Pull out the spacer slats and remove some sand around the block to get the space between box and slab a few inches deeper than the slab ( 6" to 8"). A shop vacuum and thin nozzle is the simplest way to get the sand out.
Pour hot roofing tar or asphaltum in the gap between the box and slab edges. Tape off the floor 6" around the gap to keep it neat)
Make a base from 4X4 or 6X6 timbers that fists in the recess at the top of the box (this base will stick up above the floor), and bolt it together with through rods in at least 3 places. Drill the timbers so they will allow the threaded rods to go through it ( use your template). If you drill oversize holes, pour hot tar down the gap around the rods after the base is in place in the box.
Mount the LG to the base. Some folks put a sheet of hard neoprene or horse stall matting between the LG and the base.
This sounds like overkill, but the isolation box will support the LG well and keep a lot of the impact vibrations from shaking everything in the shop.