Thread: 55t press

I can visualise the flat bar being in tention between the head beam and table when pressing. But I would have thought that with the downward pressure on the table that below table height the FB to be under compression?

Some Bolt info: John was saying that M20 is about the biggest you will commonly see in structural steel conections due to the fact that the guys installing it only have Podge and impact wrench to torque up. Going past M20 requires more torque and more equipment.

M6 fine and coarse. I tried 2 local fastener suppliers, both saying that in M6 there is only one pitch. That being M6 x 1.0 metric coarse. Not that M6 metric fine does not exist, but that you can only buy bolts in M6 x 1.0...very few applications for M6 fine. Seems that there is a bigger range in UNC/UNF stuff than metric....

I was trying to explain why the load is only kept up the top in words, but I figured a diagram is easier. I hope this helps, if it doesn't make sense, I can probably explain it a bit easier...

Basically though, the force from the press stays in the top section of the frame, between the table and the head. The only forces which act below this point should be self weight. There are diagrams and equations attached if it helps to make more sense. You are correct that below the table will be in compression, but it's negligible, as far as I can tell.

Hopefully the attachment works too!

-Martin

Whoops, I just realised I drew L1 and L2 backwards. Think of the arrows being pointed in the opposite directions, so there's tensile rather than compressive forces happening in the top section of the frame... The same logic still applies though.

-Martin

Originally Posted by uninformed

I can visualise the flat bar being in tention between the head beam and table when pressing. But I would have thought that with the downward pressure on the table that below table height the FB to be under compression?

Some Bolt info: John was saying that M20 is about the biggest you will commonly see in structural steel conections due to the fact that the guys installing it only have Podge and impact wrench to torque up. Going past M20 requires more torque and more equipment.

M6 fine and coarse. I tried 2 local fastener suppliers, both saying that in M6 there is only one pitch. That being M6 x 1.0 metric coarse. Not that M6 metric fine does not exist, but that you can only buy bolts in M6 x 1.0...very few applications for M6 fine. Seems that there is a bigger range in UNC/UNF stuff than metric....

Think of it this way, the weight of the press is pushing down on the floor, no matter how much pressure you put into the hydraulic actuator the press is not going to weigh any more. (ignoring the minor mass of additional fluid pumped into the actuator) Therefore there is no additional force transferred from below the table beam onto the uprights.

It's just the opposite of trying to lift yourself by your shoe-laces. No matter how much you might strain your back, your weight on the ground doesn't change.

ok, so there is an equalling out of the load on head beam and table? Weight thus far is approx:

Ram 30kg
ram plate 48kg
4 x 250PFC 148kg
4 x 100x16 Flat 104kg

so already at 330 kg. While holes will reduce some weight, there will be more added...

Originally Posted by uninformed

I can visualise the flat bar being in tention between the head beam and table when pressing. But I would have thought that with the downward pressure on the table that below table height the FB to be under compression?

Some Bolt info: John was saying that M20 is about the biggest you will commonly see in structural steel conections due to the fact that the guys installing it only have Podge and impact wrench to torque up. Going past M20 requires more torque and more equipment.

M6 fine and coarse. I tried 2 local fastener suppliers, both saying that in M6 there is only one pitch. That being M6 x 1.0 metric coarse. Not that M6 metric fine does not exist, but that you can only buy bolts in M6 x 1.0...very few applications for M6 fine. Seems that there is a bigger range in UNC/UNF stuff than metric....

Find a better bolt shop. Most suppliers only stock standard sizes. Just like taps and dies. They will tell you that such a size and pitch doesn't exist because it is not on the standard charts. I stock M6 x 0.75 and M6 x1.0. taps and dies. In some metric sizes there are as many as five pitches in use but the buggers don't stock the fasteners. Try some of the M7 & M9 commonly used in Japanese automotive applications. "Don't exist" you will be told. "No, then how come my Kawhonotasan is full of them." The unified national system is far better than metric in my opinion. Get some 3/4" or thicker Grade 5 or Grade 8 to replace that M20 construction rubbish.

I see no advantage in going finer than the standard M6x1mm. Don't make it harder for yourself.