Another Bearing Press Thread

[440dodgechargerrt]

I'm in the process of designing a bearing press, its main purpose will be motorcycle swingarm, wheel and engine/gearbox bearings.

Here are some CAD drawings so far, have a few adjustments I might make like moving the triangular reinforcements so I can drop the 'table' thingy all the way down so it rests on the bottom cross member.

I'll either FEA it or do hand calcs to work out the max load and redesign if required.

Design at the moment consists of 60mmx40mmx5mm rectangular section and 5mm hot rolled plate.

The pins holding locking the 'table' in position aren't dimensioned on the CAD but will be at least 20mm diameter high tensile steel (not mild).

 

[440dodgechargerrt]

I think I'll also make it so it is possible to pull the table thingy off (tilt it at an angle) and replace it with two lengths of rectangular section and have a central gap.

 

[440dodgechargerrt]

Just done basic beam bending calcs on the horizontal sections, will need to beef it up a bit.

σ = My/I thus M = σI/y

I = (((40E-3)*(60E-3)^3)-((30E-3)*(50E-3)^3))/12 = 407.5E-9 (m^4)

M = PL/4 (at mid of span)

sub

M = PL/4 into M = σI/y gives: PL/4 = σI/y

Rearrange

P = (σ*I*4)/(L*y)

σ = σ yeild = 275Mpa = 275E6 N/m^2

y = y max = 30mm = 30E-3m

P = (275E6*407.5E-9*4)/(695E-3*30E-3) = = 21,498.8N = 2191.5kg

So just under 2.2 tonne.

Could go 80x40 (5mm or 8mm), but how much force is needed for motorcycle wheel bearings?

 

[440dodgechargerrt]

Should add thoses calcs only take into account the bending moment not shear, max force for pure shear is around 123750N or 12,615kg.

I have decided I will design the two load bearing horizontal beams as trusses which will remove bending and all sectons will be in either tension or compression. Didn't really want to do a truss as it adds a fair bit of extra height to what should be a compact press, though max load could be around 25tonne.

Will add CAD of revised design soon.

 

[440dodgechargerrt]

Press MKII

Made from 60x40x5 (mm).

Any comments welcome.

 

[graffian]

Unless your only doing something it's suitable for, I would
make the table in two pieces, with a gap down the middle.

I was going to make mysefl a new press, something like this:

 

[rkde]

MK2 looks a little complex and all of it looks like it could be made a lot cheaper, standard SHS or RHS and where required gussets on the side. Remove the 30mm rad around the top

As it stands both of your designs are a little too complicated to make and not really cost effective but a good basis. I'm on holiday and CBA to sit at the cad and draw up a simple system so I say go and look see what is already out there

40 SHS will do 5T, though it all depends on the quality of the welds.

Keep it simple and take a look at the stock clarke units and others to see how they have done it, triangulation will be a waste of time and any basic linear FEA package will show it to be not required.

I would personally go 40SHS and gusset the top corners, the table I would do out of channel section either side and join it with a c section between. 20mm dia pin is right for up to 10T using high tensile steel

Do a quick fea and see what you need. What load are you aiming for? 10T will do almost everything and 5T is normally all you required

If you are using a bottle jack consider a return spring too

 

[RichardM]

Do bottle jacks work up-side down?

 

[rkde]

yes they do, they just don't return back without a spring

 

[brightspark]

why re invent the wheel. as said just go look at them in machinemart and take measurements and the jobs done

 

[440dodgechargerrt]

Thanks for the input, I'll give you my reasoning tell me if it is flawed.

These are the tools I have to work with:

I have a miter saw (rage 3) which will cut angles in steel, 9in angle grinder, 2hp Alfred Herbert Drill Press (should drill 20mm), Oxford RT110 and a MIG welder.


My plan was to use 60x40x5 (mm) for almost everything to reduce cost, at the moment I need about 6.1m so if I'm careful could get away with one section which will cost £30 - £50 in virgin steel (bank holiday Monday so can't call the stockest).

Has anyone made a MM press copy if so how much would it cost in virgin steel?


I know where your coming from with the triangulation at the bottom as there should be no sideways force causing it bend in fact very little load of any kind at all just the weight of the press.

I can ditch the 30mm radius, I was going to use a 60mm hole saw to do it.

Yes the Central gap is great for removing bearings from shafts etc, I'm trying to think if it would beat the table for what I want to use if for.

Yes, I think you have to fit a snorkel to the oil pickup and then they work but as rkde said without a return spring you need to push it up by hand.

 

[440dodgechargerrt]

Woops missed one section out, make that 7m and two lengths. Might have a plan for the excess.

 

[440dodgechargerrt]

OK so been down to MM and had a look at their presses.

Looked at the 10Tonne bench as that's all they had on display.

The horizontal section were made of 410(ish)mmx75mmx8mm
Holes for pins were 20mm

Just done beam theory calcs on the horizontal section using von Misses stress formula to take into account shear and bending moment. As long as I have not made a mistake I come up with a maximum point load of 1.666 Tonne per section (at mid span), the load is spread over two such sections hence 3.333 Tonnes.

The press is sold as a 10Tonne press but structurally the horizontal sections are only good for 3.3 Tonne.

I understand in reality the load is unlikely to be a point load more often it would be a distributed load over a proportion of the section and that only a small area is under such high stress resulting in localised yielding which would distribute the stress limiting actual values. However I have applied no safety factor to this value, it is 3.3 Tonne at a safety factor of 1!

 

[rhubarb7]

I bought a 12 tonne Sealey copy, floor standing about 5 years back, it cost £75.

Does the job, and gets used a lot.

It has 2 movable plates, your design with a fixed solid plate will be no good when trying to do car wheel bearings.

 

[440dodgechargerrt]

Mk3 will include a gap, though I'm going to keep the truss design as it is far superior from a structural stand point and my miter saw can cut angles very fast so shouldn't take too long. I'll have to re-draw it on CAD, will order the steel next week.

 

[s410man]

why re invent the wheel. as said just go look at them in machinemart and take measurements and the jobs done

i dounbt mm have invented the perfect press

it may be a good platform to start with but i would think some aspects could be improved

 

[brightspark]

i dounbt mm have invented the perfect press

it may be a good platform to start with but i would think some aspects could be improved

take the basics then and then improve to your satifaction thats all i do

 

[oilcooled :)]

yes they do, they just don't return back without a spring

not all of them oil reserve needs to be above the lift chamber ?? it wont be when the jacks upside down, need to drill and tap the side of the jack for an external reservoir.

 

[the snooper]

Do bottle jacks work up-side down?

yes they do, they just don't return back without a spring

the upside down bottle jacks ive seen people use on here have been modified with a resovoir above to keep the jack body full.
if you just had the body full once you start pumping the oil level will fall away from the pump intake and will no longer work

 

[Wedg1e]

why re invent the wheel. as said just go look at them in machinemart and take measurements and the jobs done

Graffian's design up there ^^^ is a dead ringer for the Machine Mart Clarke 10T thing we've had at work since the dawn of time. It's only on its second pump and third set of jack seals and the 'table' is bent like a banana but it still works.

To the OP: motorcycle wheel bearings aren't normally in that tight that they require a press to put in... normally you just drift them out and tap new ones in. A lot of modern bike wheels are so designed that you can't access the inside face of the bearings to drift or press, you have to use an expanding puller and slide hammer them out.