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clutch
07-03-2009, 07:47 PM
I'm repairing a lathe that had the keyway torn out. I've welded it back up and turned it down to clean it up.

Between my turning down slightly and the wear in the pulley, I have a over sized condition. Pulley is cast iron.

I'm thinking of boring out pulley for an insert pressed in that matches the shaft I repaired.

What is the best way to pin it in place?

Thanks,

Clutch

pipeclay
07-03-2009, 08:13 PM
You could make your Bush slightly oversize depending on its diameter(rule of thumb is .001" to the inch) and Heat your pulley so that the bush slips into it,you could even have the bush in the freezer to shrink the bush to assist in your interference fit.
After woulds if you are still concerned about your bush comming loose you could Scothch dowel it with either a small grub screw or roll pin.
Just drill one or two small holes to suit grub screw or roll pin in the centre of the pcd of the gear and bush repair.

tattoomike68
07-03-2009, 08:27 PM
Bore the whole hub off, make a big shoulder bushing, weld it in with econocast rod. once its cool bore and key it and call it done.

Thats what we call "bore and slug."

Cast iron welding is not hard to do, machine chamfers for weld, pre heat with a torch. weld it with at least 100 amps. peen the weld with a chipping hammer till your arm hurts. do a post heat and throw it in a bucket of ashes so it cools real slow. the weld should turn out as ductile and machinable as you could ever ask.

Also it would be wise to go ahead and weld up the shaft and turn and re-key it too. make all the parts back to spec.

Al Messer
07-03-2009, 09:31 PM
Ever think of using Loc-Tite?

pipeclay
07-04-2009, 03:25 AM
How much interference are you going to have or is it going to be a sliding fit.
Does the part get hot,this can weaken the loctite.

Evan
07-04-2009, 05:30 AM
A pulley? Is this for a drive belt? What is the ID of the hole and the OD of the pulley? If for a Vee belt the OD is at the bottom of the groove.

Gray cast iron has poor tensile yield strength. It ranges from about 9ksi to 25 ksi depending on grade. Ultimate Tensile strength is about 1/3 the compressive strength. Using an interference fit can crack the iron if the OD is not a lot bigger than the ID, especially since the insert will have much greater compressive strength than the part has tensile strength.

oldtiffie
07-04-2009, 07:07 AM
Let's go back to basics and "square one" and not get side-tracked by the possibly unnecessary more exotic options - again.

Instead of boring and pressing or welding or using Loctite alone, why not just clean the bore up face-off, than screw cut the bore. Make a flanged screwed sleeve to suit and screw it in to pre-screwed gear right up hard to the flange. By all means use Loctite (correct grade of course) and then bore - and key? - the bore to suit the shaft. Only thing to watch is the direction of rotation of the pulley so that it tightens the thread instead of loosening it. Think right and left-hand threads on grinders and why they are used.

You can make the screwed sleeve from any material that suits you. Just like the thread on a lathe back-plate fitting on the spindle screwed nose.

No need for press fits or welding or shrink-fitting and possible cast-iron fractures.

If needed a pin or screw can be fitted to "keep" the flange if needs be - but I'd doubt it would be necessary.

clutch
07-04-2009, 06:39 PM
You could make your Bush slightly oversize depending on its diameter(rule of thumb is .001" to the inch) and Heat your pulley so that the bush slips into it,you could even have the bush in the freezer to shrink the bush to assist in your interference fit.
After woulds if you are still concerned about your bush comming loose you could Scothch dowel it with either a small grub screw or roll pin.
Just drill one or two small holes to suit grub screw or roll pin in the centre of the pcd of the gear and bush repair.

Evan made a reference to press fits and cast iron, I have no problems with a press fit, just don't want to crack it.

The grub screw, are you talking about tapping the hole short of though and setting a screw coated with locktight?

The roll pin also sounds interesting, never heard that one before.

Clutch

clutch
07-04-2009, 06:43 PM
Bore the whole hub off, make a big shoulder bushing, weld it in with econocast rod. once its cool bore and key it and call it done.


That is an interesting suggestion.


Also it would be wise to go ahead and weld up the shaft and turn and re-key it too. make all the parts back to spec.

The minor reduction in diameter isn't that big a thing. The chance that I mess up the threads on both sides of the shaft is very high. Lathe is not heavily stressed.

Clutch

clutch
07-04-2009, 06:44 PM
Ever think of using Loc-Tite?

How well does loc-tite work with an interference fit?

Clutch

clutch
07-04-2009, 06:49 PM
A pulley? Is this for a drive belt? What is the ID of the hole and the OD of the pulley? If for a Vee belt the OD is at the bottom of the groove.

Gray cast iron has poor tensile yield strength. It ranges from about 9ksi to 25 ksi depending on grade. Ultimate Tensile strength is about 1/3 the compressive strength. Using an interference fit can crack the iron if the OD is not a lot bigger than the ID, especially since the insert will have much greater compressive strength than the part has tensile strength.

I errantly used gear when it is a pulley. There is enough wall to press in an insert. I'm not against using CI rod and welding it in. As it is, the ~ 1 inch shaft uses a 3/16w by 7/8 dia woodruff key.

I can buy a piece of 2" cast iron rod and some cast iron welding rod to use TT..Mike..'s suggestion.

clutch
07-04-2009, 06:52 PM
Let's go back to basics and "square one" and not get side-tracked by the possibly unnecessary more exotic options - again.

Instead of boring and pressing or welding or using Loctite alone, why not just clean the bore up face-off, than screw cut the bore. Make a flanged screwed sleeve to suit and screw it in to pre-screwed gear right up hard to the flange. By all means use Loctite (correct grade of course) and then bore - and key? - the bore to suit the shaft. Only thing to watch is the direction of rotation of the pulley so that it tightens the thread instead of loosening it. Think right and left-hand threads on grinders and why they are used.

You can make the screwed sleeve from any material that suits you. Just like the thread on a lathe back-plate fitting on the spindle screwed nose.



I think that is overkill but if you check
http://wess.freeshell.org/clausing/Clausing.html

You will see I used that idea repairing a sheave once upon a time.

Clutch

Evan
07-04-2009, 08:27 PM
I can buy a piece of 2" cast iron rod and some cast iron welding rod to use ...


One note about cast iron welding rod; the kind that is commonly available here is what I used to hard face the bucket teeth on the back hoe. It is entirely unmachinable except by grinding.

John Stevenson
07-05-2009, 06:20 AM
Gordon Bennett what a palaver over a 10 minute job.

It's cast iron so no interference fits or welding if you don't want it to crack.

Bore out, make sleeve for slip fit, loctite in and then drill two holes on the joint so 1/2 in in the pulley, half in the sleeve, fit a couple of Allen grub screws and nip up.

If you have no grub screws fit a long ordinary screw and cut the excess off, it isn't like it needs to be disassembled at any point does it ?

.

Rustybolt
07-05-2009, 09:44 AM
How well does loc-tite work with an interference fit?

Clutch

Locktite cures in the absence of air. Once together you'll have the devils own time getting them apart.

lakeside53
07-05-2009, 11:57 AM
If you want to break permanent loctite (like 26x or 27x), heat it to 400F...

I just repaired a really bad (and expensive) 4 groove cast iron pulley by boring out the entire center, and replacing it with a custom "hand press" flanged insert that was bolted in place. It will also be held by loctite (620) - I put 5 1/4-20 bolts though, but 5hp and instant reverse gets me worried.

Timleech
07-05-2009, 01:56 PM
Originally Posted by clutch
How well does loc-tite work with an interference fit?

Clutch


Locktite cures in the absence of air. Once together you'll have the devils own time getting them apart.

But if it's an interference fit, surely (almost) all the loctite will be displaced?

I believe there are ideal clearances specified for different grades.

Tim

John Stevenson
07-05-2009, 05:07 PM
But if it's an interference fit, surely (almost) all the loctite will be displaced?

Tim

Only if it's done on a South Bend to microns precision, the rest of us mere mortals have to put up with rough arsed valleys and troughs that hold the loctite.
I sleeved a 8 groove B section pulley a few months ago, about 6" long and 48mm bore [ roughly 2" for the metrically impaired ] I fitted two M10 allen grub screws at each end and this was on a 75 HP pump motor at a local sewage works, that got them out the sht ;)

.

Evan
07-05-2009, 06:38 PM
Only if it's done on a South Bend to microns precision, the rest of us mere mortals have to put up with rough arsed valleys and troughs that hold the loctite.


Dead on, John. I don't use Loctite for that very reason. I just finished turning this a few minutes ago. It's a piece of crap steel schedule 40 pipe from India. This is how it turns right through the scale. It hasn't so much as been touched by a cloth and was turned dry.

http://ixian.ca/pics6/finish1.jpg

radkins
07-05-2009, 07:22 PM
Most of the economy cast iron rods are absolutely not machinable! If the weld has to be machined or worked in any way except maybe by grinding then you must be CERTAIN that you are using a machinable rod for cast iron such as Ni99. While post-heat can be of great importance when welding iron castings it will have little effect on the machinabilty of the weld itself and will NOT make an otherwise non-machinable weld machinable!

tattoomike68
07-05-2009, 08:33 PM
Most of the economy cast iron rods are absolutely not machinable! If the weld has to be machined or worked in any way except maybe by grinding then you must be CERTAIN that you are using a machinable rod for cast iron such as Ni99. While post-heat can be of great importance when welding iron castings it will have little effect on the machinabilty of the weld itself and will NOT make an otherwise non-machinable weld machinable!

Econocast 55 machines great just like the cast iron itself. Its used alot for rebuilding cat tractor parts (done tons and tons of them). Another trick is to undercut the old workhardend worn cast away before welding, it not olny gets it clean but you dont have to machine the mix of the two metals and are cutting weld only.

there are lots of small tricks you can do to make cast iron weling a no hassle job. the right rod helps big time. dont be shocked by the price of good cast rod, you get what you pay for.

tattoomike68
07-05-2009, 08:39 PM
Dead on, John. I don't use Loctite for that very reason. I just finished turning this a few minutes ago. It's a piece of crap steel schedule 40 pipe from India. This is how it turns right through the scale. It hasn't so much as been touched by a cloth and was turned dry.

http://ixian.ca/pics6/finish1.jpg


Black pipe machines great, but its not cast iron. who know what it is for sure but it does its job just fine and thats all that matters. the chips sure dont look like iron.

stoneysstarters
07-05-2009, 08:49 PM
Have you tried the "green" loctite. I can't remember the number but it is a wicking grade to be put on after assembly. I wish I could find penetrating oil that soaks in half as good.

lakeside53
07-05-2009, 10:04 PM
Here's my pulley bore repair.

Massively slogged out key way, 50 thou taper on the bore. OEM replacement was $415 plus tax and shipping.. Phooey to that. I found a close equivalent from Browning, but that would have needed machining to suit. Nothing to lose except a couple of days of my life, so...

http://i238.photobucket.com/albums/ff150/lakeside53/polamco/DSC_8370Medium.jpg


Machined the entire center out. Cast iron machined beautifully.

http://i238.photobucket.com/albums/ff150/lakeside53/polamco/DSC_8371Medium.jpg



Thought I was very smart by machining the center bore a thou undersize to help with final fitment (brake hone) and some shaft taper. Great idea.. so I borrowed a 6mm broach... but that just meant the broach bushing won't fit. grrr.. had to make one... Wonder if I'll ever need a 1.179 diameter bushing again? lol.

http://i238.photobucket.com/albums/ff150/lakeside53/polamco/DSC_8382Medium.jpg


I made 2 inserts... The originally was made of 1140; machined nice. Piles of short blue chips. But... screwed up the final bore.., Rats.. no more 1140... Made another from 4340 - took twice as long... huge pile of nasty ribbon swath.

Done....
http://i238.photobucket.com/albums/ff150/lakeside53/polamco/DSC_8386Medium.jpg

radkins
07-05-2009, 10:14 PM
dont be shocked by the price of good cast rod, you get what you pay for.


The right rod will make all the difference in the world and will machine just fine, just as you say, and the wrong rod will make all the difference too, just in the opposite way! When using the wrong (high iron content) rod the weld itself will machine OK but the transition area from the weld bead to the base metal will be extremely hard and unmachinable. I know what you mean about the cost of the machinable rods, I just paid nearly $42 a lb for the last ones I bought! :eek:

lakeside53
07-05-2009, 10:39 PM
WRT black pipe.. I haven't had much luck with the stuff we get locally -Korean typically. To me it turns much like 1018.

Evan
07-06-2009, 12:56 AM
There is a trick to it. The finish on the pipe is real but John is having me on and I am getting him back. :D

lakeside53
07-06-2009, 01:33 AM
Thank god for that! I was getting worred about the performance of my equipment again:D

oldtiffie
07-06-2009, 03:30 AM
Originally Posted by Timleech

But if it's an interference fit, surely (almost) all the loctite will be displaced?

Tim


Only if it's done on a South Bend to microns precision, the rest of us mere mortals have to put up with rough arsed valleys and troughs that hold the loctite.
I sleeved a 8 groove B section pulley a few months ago, about 6" long and 48mm bore [ roughly 2" for the metrically impaired ] I fitted two M10 allen grub screws at each end and this was on a 75 HP pump motor at a local sewage works, that got them out the sht ;)

.



Dead on, John. I don't use Loctite for that very reason. I just finished turning this a few minutes ago. It's a piece of crap steel schedule 40 pipe from India. This is how it turns right through the scale. It hasn't so much as been touched by a cloth and was turned dry.

http://ixian.ca/pics6/finish1.jpg

Nah - you gotta be wrong Evan.

No re-bar or spark plugs etc. (as "everybody" knows there always is) in that crap Indian pipe that I can see. For it to be THAT good it just hasta be good old American product and know-how.

That sort of micro (micron??) finish is simply beyond a SB lathe let alone some hick in the wilds of Canada.

Repent ye sinner - repent.

You are going to need lottsa plenary indulgences and penance to get absolution in this scandalous infamous heresy in this instance for the scam that you try to inflict on honest simple HSM-ers.

Shame!!! Shame!!! Oh the shame of it all!!!

Nice job though!!!

oldtiffie
07-06-2009, 03:59 AM
.................................................. ...................

tattoomike68
07-06-2009, 05:28 AM
The right rod will make all the difference in the world and will machine just fine, just as you say, and the wrong rod will make all the difference too, just in the opposite way! When using the wrong (high iron content) rod the weld itself will machine OK but the transition area from the weld bead to the base metal will be extremely hard and unmachinable. I know what you mean about the cost of the machinable rods, I just paid nearly $42 a lb for the last ones I bought! :eek:

get the good stuff and dont mess around, just like you did. there is free machining cast iron rod but you pay big time. its there and if you need it you buy it. it sure help if you done it 100+ times..

radkins
07-06-2009, 11:24 AM
get the good stuff and dont mess around, just like you did. there is free machining cast iron rod but you pay big time. its there and if you need it you buy it. it sure help if you done it 100+ times..



Just a note about the cost vs quality of the non-machinable rod, because the machinable rod is painfully expensive most people assume it is going to be the strongest and best choice for problem welds even when machining is not going to be required. This is not necessarily true however and for a repair that will not require machining these rods may not be required, the extra cost does not buy better crack resistance. I have seen several times situations where someone spent a lot of money buying machinable rod when it was not necessary because of the thinking that since they cost so much they must be better, well they are in a lot of ways but if cracking of the repair is the problem they will not help.