Help needed with my maths please

I’ve tried but can’t calculate the following could someone help ?

What diameter horizontal steel bar 4ft long would comfortably support 3/4 of a ton ?

This is my milling machine which I need to lift a couple of inches off 2 pallets It’s in a confined space so can’t use an engine crane/pallet truck etc so am planning to use a chain block and and acrow props which I can just get into the available space. I have tried wood but the size takes up too much room hence the steel rod which may give that extra inch or two.

thanks

At 4' I would use a length of scaffold pole, tube will be better than bar. A small I beam ?. Just be VERY careful and if it shows signs of bending much then use something bigger/thicker. Good luck Noel.

Sonic did his machine recently, you cut out the pallet once its in position

**LINK**

What stops the Acrows falling over?

Move it back to somewhere you can lift it. Then move it back at ground level? Only need bars/pipes underneath it in that scenario

In your current position it will depend on where the mill is suspended from. Single point in the middle or two points virtually over the supporting structure. It’s not, so far, really a maths problem at all.

When I installed my Myford 254 in a room which measures 2.6 x 2.0 m with the door at the end of a long wall, the tricky part was getting the engine hoist out from underneath it. The only possibility seemed to be to leave it on some paving bricks.

Then I had to remove the bricks.

I used a 2-ton bottle jack and a bit of 2" x 2" (maybe bigger) timber. I drilled a hole in the end of the timber so that it could not slip off the jack, and made a notch in the other end. This enabled me to jack up each end separately just enough to remove one brick (or pair of bricks) at a time.

As suggested above, you would need to cut the pallet.

The advantage of my method is that only around half of the weight of the lathe had to be supported.

I would not even think of supporting it under a bar. It could bend catastrophically, or the whole rig could topple.

I would prefer to dismantle it then the parts are not only lighter, but smaller.

Has the machine got adjustable feet - or holes that can accommodate feet? Use the feet to lift it off the pallets - some cutting of the pallets may be required.

Or just set fire to the pallets

Math

Using a beam calculator (Free Beam Calculator | ClearCalcs with moments of inertia from Second Moment of Area Calculator (amesweb.info))

A 1200mm length of scaffolding pole (48.3mm) rigidly supported at each end and subject to a 750kg ( 3/4 tonne) load in the centre is going to flex downwards about 10mm. The same diameter solid bar would flex about 5mm.

A 100mm diameter bar would only flex about 0.2mm. However I'm not at all sure how you would get a 84kg bar up there in the first place!

Depends how you define comfortably!

Edited By Peter Cook 6 on 16/05/2023 19:05:20

I think it's impossible to calculate that unless you show a drawing of how the bar is loaded.

Thank you all, there is not enough height to lift the mill off the pallets so have gone for cutting the pallets in half and chocking up then lowering down...first one done and will finish tomorrow.

The acrows and 6x4 are up tight against the garage roof so can't topple and I'm only lifting 1/2 total weight at a time..looking forward to getting to use it at last...and will end up with 4 pallets.

Please supply photographs of the problem.

My feeling is that you should use jacks but I would not be firm about this without seeing the difficulty.

As for your first question the diameter of a 4 foot long solid steel bar carrying 3/4 ton at its mid point with a deflection of 1" would be to be 2.8". You can work out the maximum stress (too late in the evening).

JA

Peter: My understanding of the arrangement is that the beam ends would be simply supported.

Edited By JA on 16/05/2023 20:56:28

Carl, just a reminder what can happen if you use Sonic's method and get it wrong.

That picture of the Tom Senior is sobering but it all went according to plan. I lifted the front made safe and cut 1/2 the pallet away chocked up and then to the back for the same. There was enough room to do that and less than full weight.

The pallet that was on the bottom, it was on two, was the trickiest as there was not much space to cut it in but I took my time and now its down. It was quite top heavy and wanted to tilt to the front right but was never near the point of no return. In all the excitement I missed the 'before' pictures but have a couple during so will have to start an album.

I'm curious about the motor wiring it seems to be wired Delta using red, blue and green with the fourth wire, which is white, unused. Looking at the old colours these colours were used in Australia and Canada ?

Thanks again for all the comments.