Hollow tube rotary welding table

[shedhappens]

I really hate it when I use a lathe as a welding jig so I thought I would do something about it.
I decided to make this with a hollow tube (88mm I.D) as it should make it quick and easy for welding flanges onto shafts,
the hole in the shaft/faceplate will be fitted with a removable bush/plug when the big hole is not required and can be made to centre small jobs.
The front and rear bosses will have 4 bolts in them to centre material in the tube in the same manner as a 4 jaw chuck,
I have fabbed a face plate that will be welded the front boss.
The tube will rotate within 8 x 6204 brgs, 4 at front and 4 towards the rear, think pipe roller, and a couple more
for thrust, rolling on a disc.
Yeah I know some will think that is rough but that is what I have got and it won't have much load on it and
it only spins at low revs anyhow.
I was just going to use a toothed belt drive reduction to the shaft with a speed controller http://www.jaycar.com.au/Power-Products-Electrical/Power-Conversion-%26-Transformation/Specialty-Power-Conversion-%26-Transformer-Products/12VDC-8A-Dimmer-Motor-Speed-Controller/p/MP3209 but it needed a bit more gear reduction as at very low rpm the motor was a bit weak, so with the change of plans it will now also get a neutral position and a shaft lock by sliding the gear set out of mesh.

I decided to make a gear reduction out of Briggs & Stratton camshaft gears, I was going to press the ring gear onto the boss with some loctite, I'm having a bit of a brain fart about this ?
Both parts are machined to 3.700", I wanted a light press fit but now I don't think that is a good idea as the ring gear is CI and
could crack, so what is the consensus about how much clearance I should give it in order for the ring gear to be slid onto the boss and be retained by loctite alone ?

shed

[RayG]

The smaller the gap the better, you might be able to find some loctite data on-line, but a sliding fit would be a good start.

One thing to keep in mind is that loctite comes loose at high temperatures, so it might not work if it's close to where you are welding.

Another alternative might be to go for a heat shrink fit?

PS. Looking very slick so far :2tsup:

[Gammaboy]

Braze it?

[Stustoys]

I decided to make a gear reduction out of Briggs & Stratton camshaft gears,

Do you still have the matting part from the B&S? what size it is?

If you want to go the loctite route
Q5: What is the optimum fit for using anaerobic retaining compounds if I want to maximize my shear strength?A: A slip fit would be suggested. The optimum fit for thinner products like LOCTITE 609 & 603 is 0.001-0.003' on the diameter. The optimum fit for thicker products like LOCTITE 620 & 638 is 0.002-0.004' on the diameter.

[shedhappens]

The smaller the gap the better, you might be able to find some loctite data on-line, but a sliding fit would be a good start.

One thing to keep in mind is that loctite comes loose at high temperatures, so it might not work if it's close to where you are welding.

Another alternative might be to go for a heat shrink fit?

PS. Looking very slick so far :2tsup:

G/day Ray, the ring gear is to be fitted at the far end of the shaft away from the heat, also I think that mounting work on standoffs will reduce heat transfer.
I thought about the heat shrink fit caper but the gear is pretty thin and I had premonitions of hearing a little tink :rolleyes: as it cooled,
anyway now that I have bored it it wouldn't be tight enough.....

shed

[shedhappens]

Braze it?

G/day Gammaboy,
Or even silver solder, or even a stainless rod.
Unfortunately I got sick of paying rental on bottles some time ago for how much I used them.
But good idea, thanks

shed

[shedhappens]

Do you still have the matting part from the B&S? what size it is?

If you want to go the loctite route
Q5: What is the optimum fit for using anaerobic retaining compounds if I want to maximize my shear strength?

A: A slip fit would be suggested. The optimum fit for thinner products like LOCTITE 609 & 603 is 0.001-0.003' on the diameter. The optimum fit for thicker products like LOCTITE 620 & 638 is 0.002-0.004' on the diameter.

G/day Stuart, there is no mating part, in one of the photo's I put in a another camshaft just to show what the ring gear
was snaffled from.

Thanks for that data, you gave me a shove in the right direction.
This loctite looks like it will do the job nicely http://www.loctite.com.au/3320_AUE_HTML.htm?nodeid=8802649407489

Pity the local ind. supplier hasn't got it

shed

[KBs PensNmore]

Do you have access to dry ice (frozen stuff not the other), wrap the tube in plenty of news paper and fill it with the dry ice to shrink it. Then fit the gear. Have repaired a few cracked engine cylinders this way.
Kryn

[shedhappens]

Do you have access to dry ice (frozen stuff not the other), wrap the tube in plenty of news paper and fill it with the dry ice to shrink it. Then fit the gear. Have repaired a few cracked engine cylinders this way.
Kryn

Thanks Kryn, Healesville doesn't even have loctite let alone eskimo's :)
thanks m8 but I think I'll go the loctite.

shed

[Jekyll and Hyde]

Thanks Kryn, Healesville doesn't even have loctite let alone eskimo's :)
thanks m8 but I think I'll go the loctite.

shed

Bearing Wholesalers in Lilydale has a pretty good range of Loctite gear - got some 609 there not long ago. Not too sure about 620, but could be worth a phone call at least, if you're heading that way.

Also thought I'd mention, although you probably already know, Bunnings now do oxy and acetylene in a Swap and Go type deal....

[RayG]

Also thought I'd mention, although you probably already know, Bunnings now do oxy and acetylene in a Swap and Go type deal....

Thanks for that, I hadn't heard, looks like I get oxy gear finally. Still hurting from the last BOC $300+ annual rental fee for argon and argoshield..

It's about time someone gave BOC some real competition.

[Seymore Butts]

You can always try scotch keying the ring gear with a couple 4mm grub screws along with Loctite. Some Loctites take a hell of a lot of heat.



I really hate it when I use a lathe as a welding jig so I thought I would do something about it.
I decided to make this with a hollow tube (88mm I.D) as it should make it quick and easy for welding flanges onto shafts,
the hole in the shaft/faceplate will be fitted with a removable bush/plug when the big hole is not required and can be made to centre small jobs.
The front and rear bosses will have 4 bolts in them to centre material in the tube in the same manner as a 4 jaw chuck,
I have fabbed a face plate that will be welded the front boss.
The tube will rotate within 8 x 6204 brgs, 4 at front and 4 towards the rear, think pipe roller, and a couple more
for thrust, rolling on a disc.
Yeah I know some will think that is rough but that is what I have got and it won't have much load on it and
it only spins at low revs anyhow.
I was just going to use a toothed belt drive reduction to the shaft with a speed controller http://www.jaycar.com.au/Power-Products-Electrical/Power-Conversion-%26-Transformation/Specialty-Power-Conversion-%26-Transformer-Products/12VDC-8A-Dimmer-Motor-Speed-Controller/p/MP3209 but it needed a bit more gear reduction as at very low rpm the motor was a bit weak, so with the change of plans it will now also get a neutral position and a shaft lock by sliding the gear set out of mesh.

I decided to make a gear reduction out of Briggs & Stratton camshaft gears, I was going to press the ring gear onto the boss with some loctite, I'm having a bit of a brain fart about this ?
Both parts are machined to 3.700", I wanted a light press fit but now I don't think that is a good idea as the ring gear is CI and
could crack, so what is the consensus about how much clearance I should give it in order for the ring gear to be slid onto the boss and be retained by loctite alone ?

shed

[eskimo]

Thanks Kryn, Healesville doesn't even have loctite let alone eskimo's :)
thanks m8 but I think I'll go the loctite.

shed

whad do ya want me for..:?

[shedhappens]

Bearing Wholesalers in Lilydale has a pretty good range of Loctite gear - got some 609 there not long ago. Not too sure about 620, but could be worth a phone call at least, if you're heading that way.

Also thought I'd mention, although you probably already know, Bunnings now do oxy and acetylene in a Swap and Go type deal....

Thanks Jekyll, they didn't have it either so they are getting it in.
Regarding the gas, I read about it in the welding forum a few weeks back, I reckon that when the crunch comes and I need to get
gas, for whatever that may be, I will likely just get an oxygen and use LPG with the comet 3.

[shedhappens]

You can always try scotch keying the ring gear with a couple 4mm grub screws along with Loctite. Some Loctites take a hell of a lot of heat.

G/day Seymore, I am not keen on tapping into 2 dissimilar metals, and besides that I there isn't much left on the boss that the
ring gear slides onto. The 620 supposed to loose its hardness at 250 c.

shed

[shedhappens]

I ended up skimming .005" off the boss just to get the ring gear to slide onto the boss nicely, now I have the problem that when I
put the gear on and then tapped the boss onto the end of the pipe the gear locked up on the boss.
The pipe turned out of round with a tipped tool and I averaged the size to bore the boss, so I think I will chuck that pipe in the bin
and start fresh but this time use HSS to turn it, maybe machine it with the TPG ?
Black pipe isn't fun to work with.....

shed

[shedhappens]

whad do ya want me for..:?

If yer got nuffin ter do ya cud fix the leaky float valve in the evap on da shed :D

[Stustoys]

How are you going to hold the boss to the pipe?

I'm thinking you can remachine what you have. It would seem to be to big after all.

Or fit the boss to the pipe (weld?) then remachine the seat for the ring gear.

Stuart

[shedhappens]

How are you going to hold the boss to the pipe?

I'm thinking you can remachine what you have. It would seem to be to big after all.

Or fit the boss to the pipe (weld?) then remachine the seat for the ring gear.

Stuart

G/day Stuart, I wanted to press the boss onto the tube then 4 light weld's internally approx 20mm long 90 deg apart, and then slide and loctite the ring gear on.

1/ My thinking is now to start fresh and bore the inside of the pipe with the hope I can end up without it being oval, then make a plug with a centre hole to support that end in the tail stock and hopefully end up with a better machined surface to fit the boss onto. ? After the bosses are welded on to the tube I have a bit of machining to do on the tube to finish it so holding the ends well is probably a good place to start.

2/ Or maybe press the boss on the with the ring gear in place and that will give the the ring gear the interference fit, then after welding the boss to the tube give it a squirt of that loctite that wicks in after assembly ?

3/ If the gear comes loose later on at some stage, which I doubt given it isn't under much load, then could tack it in place with a ss rod ?

4/ There is quite a bit of stress in that black pipe, so maybe I need to stress relieve it first ? Ho hum ???

shed

[Stustoys]

Hi Shed


G/day Stuart, I wanted to press the boss onto the tube then 4 light weld's internally approx 20mm long 90 deg apart, and then slide and loctite the ring gear on.

So why not do that with what you have?(remachining the seat after welding, you can make a plug to fit the boss.)

Another idea set the the boss(or the tube) and relieve the bore "under" the gear.(it looks to be a pretty thin wall there). Then the press fit is taken by the thick part of the boss and should much less effect on the gear seat size.


2/ Or maybe press the boss on the with the ring gear in place and that will give the the ring gear the interference fit, then after welding the boss to the tube give it a squirt of that loctite that wicks in after assembly ?

I dont like this idea. You'll have unknown interference and not wanting interference on the gear is how we got here ;).

Stuart

p.s. I dont know how big your lathe is but is it possible you've tighten your 4jaw(?) to much and deformed the tube?

[shedhappens]

Hi Shed


So why not do that with what you have?(remachining the seat after welding, you can make a plug to fit the boss.)

Another idea set the the boss(or the tube) and relieve the bore "under" the gear.(it looks to be a pretty thin wall there). Then the press fit is taken by the thick part of the boss and should much less effect on the gear seat size.


I dont like this idea. You'll have unknown interference and not wanting interference on the gear is how we got here ;).

Stuart

p.s. I dont know how big your lathe is but is it possible you've tighten your 4jaw(?) to much and deformed the tube?


Yes Stuart it is all pretty thin, there is not much to play with and I'm not really happy with the tube.
It's hard not to deform the tube, so I really need 2 plugs, 1 inside the tube at the chuck end also.
I machined the tube in my macson lathe as that has fixed steady that would accommodate the tube, the tube being out of round to start with doesnt help, but I think if i can get a reasonable bore at each end and the use a centering plug for the rest of the machining i might get somewhere, I would like that boss to very lightly press on.
Then I spoze I could still take a whisker off the boss for the gear after it is welded.

thanks... shed