Wood is fine..... Look at the wood trestles that hold up several 100 ton coal cars at a time, with supports on 10 foot centers or so.
You get a HUGE advantage from using a deeper beam....... I think we might have had this conversation here before..... Get a couple of 2 x 12 and block them apart..... you can lift a lot with that, I refer you to the Forest products lab book for the exact amounts. Also are likely in Machinery's Handbook, or Kent's.
Blocking them apart gives them more stiffness sideways so they done't "trip" sideways and fail.
DO YOUR RESEARCH..... do NOT ask us as your only source of info, you will get everything from the true story to wild optimism, and equally wild pessimism.
Know-nothing mechanics have been pulling engines with a chain over a rafter tie for a hundred years..... often they "won", but a few didn't. Do your hiomework and you will be OK.
Fail to do it, or believe what WE say, and you may end up under the busted pieces......
Zig instaed of Zag
As others have mentioned your mill is not that heavy in the scheme of things. Personally I wouldn't give it a seconds thought to moving it in myself and I'm no giant.
Why wast time and money making a lifting device that will not be used again? Rather I would spend that time and money making a very robust set of stairs to your cellar. This investment of time and money will pay you back forever. A custom ramp that works with your staircase and you are ready to go anytime you want.
My machine shop is in my basement for now and I live in a century home with 6 stairs to the basement. I've brought in two machines that each weighed in at the roughly 1350 to 1500lb mark, They were broken down to components when possible but several pieces still weighed well in excess of 300kg. Everything went well, unless of course having the lathe on the stand with the chip pan leaning up against the wall could be considered a problem!
The real lifting issue for you will likely be getting machines on bases once you're in the basement.
I did do some research but after a load of span tables all giving values in psf I was none the wiser.
The stairs I am building will be fairly steep and quite narrow and they will end 3ft from a brick-wall, with the reinforcements I will have to do to hold up the floor above before cutting the hole.... not much room left.
Looks like I will be making the wood gantry and rely on overkill with glue, bolts and reinforcement to make sure.
Once I get the cellar shop up and running I will be making a couple of cnc machines(one router and one fixed gantry mill) down there made from epoxy-granite and concrete(base) so I am really looking forward to the move.
Will be posting pics here and on cnc zone of the build
While I have nothing to add regarding the aspect of building the gantry
Originally Posted by MasterMaker
device from wood, I wonder whether one should be so quick to discard
the prospect of using steel as the gantry material?
Is there any chance that you could select steel sections that could
be repurposed once no longer needed for the gantry? Perhaps as
raw material for work benches or shelves? Maybe for future shop
Rather than using prime steel shapes, could you perhaps adapt salvage
material originally intended for some other purpose. Frame sections
and crossmembers from an auto chassis comes to mind, although there
is every likelihood that other materials might present themselves during
a trip to a scrap yard.
MasterMaker, getting right back to the overall picture:-
You have this machine that you need to lower down through a hole in the floor and I presume this hole in the floor is indoors?
This is what I would do. First I would lay a couple of strong timbers across the hole, depending on the timber 4x4s may be suitable or I would get some 6x2 and nail them together to make 6x4 to lay across the hole on their narrow sides.
Then I would move the machine onto these timbers but first I would put some nails into the floor or the framing of the hole to prevent the timbers moving at a critical time.
Once the machine is safely in place on the timbers I would build a wooden structure like a tripod but with four legs over the machine with the legs firmly fixed so that they cannot slip on the floor. I would make this structure as tall as the overhead clearance would allow.
I would hang my chain block from the apex and lift the machine off the timbers and when I am confident the structure was strong enough and the machine safely suspended I would remove the timbers then lower away.
All good advise above but have you taken a good look at where you are going to set the lifting device? Are your floors strong enough to support the Aframe and the mill? Just wanting you to consider the whole picture.
no neat sig line
Wood is pretty strong in compression, not nearly so strong in tension. I'd suggest Douglas Fir, probably a 2X8 on edge would work for the cross beam. I'd probably nail & glue two pieces side by side. Go through the pile at the supplier, and try to minimize the knots.
Originally Posted by rohart
My advice is just FWIW, probably about what you paid for it!
Why not use the material thats gonna be cut for stair carriges/stringers.Around here they're at a minimum of 2x10's(which suck and is why we use 2x12),and we use 3,typically?
Next option,rent a metal scaffolding.........but I'd reccomend anyone even remotely connected with any construction or "homey" efforts to BUY the bloomin things.They assemble/dis-assemble in minutes and can be used for purt-near everything.
Next scenerio,one that I would take is make the stairs part of the equation.IOWs they would act as the tracks for skidding as others have mentioned or at the very least make them removable for future machines coming and going.Steel chanel for stair stringers(left in the whole) and a welded up,wheeled skid to fit.
An elegent solution may be in the attic....above stair well.Go to truss engineer with what I'm proposing.But in anycase reiforce the living chit out of attic and have an electric hoist....attach a trick light to it when not moving equip.You could slide that whole project right past the Mrs......"yeah honey the freakin light is dang heavy,engineer said we needed additional attic support.I added the hoist to make those bulb changes easier.
Be safe,don't get hurt trying to save a cpl dollars.If you ask around there has to be a shop rat somewhere that'll assist with tools and/or rigging expertease.BW
IMHO, don't use bolt. The holes create weak spots. Laminate them with glue, either construction adhesive or yellow carpenters glue, and use Screws or Clamp during setup period. - one day +.
Originally Posted by MasterMaker
Excuse me but you've got that totally backasswards.
Originally Posted by gearedloco
Wood is typically 3 times as strong in tension as it is in compression, at least parallel to the grain!
Last edited by bob_s; 04-27-2010 at 04:12 PM.