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View Full Version : braizing cast iron to mild steel



billyboy
10-20-2006, 02:59 AM
i need to slow the longditutional power feed rate down on my tom senior miller, i have a larger pulley that will fit snug over the original steel pulley but one is cast iron and the other is mild steel, can these two steels be braized together?, i would normally mig them together but i have run out of argon mix.

thanks

bill

Forrest Addy
10-20-2006, 03:17 AM
Sure. In fact that's the preferred method of permanently joining CI to steel. Bead blast the CI to remove surface carbon for the most reliable wetting.

nitearc
10-20-2006, 03:21 AM
Absolutely! you can braze cast iron to mild steel, should go quite smoothly.
Remember, clean, clean, clean, flux the two parts librally at the joint and go.
Good luck with the updated refit.
Mike

billyboy
10-20-2006, 03:28 AM
thanks fellas, ill be onto it this morning sometime.

thanks

bill

pcarpenter
10-20-2006, 12:36 PM
I hate permanently changing parts on any older machine for fear that I or someone else will want to undo it someday. Would it be more work than it was worth to turn a hub out of scrap that resembled the original pulley to braze into the bore on the larger one, preserving the original part in case your needs change?

Paul

Your Old Dog
10-20-2006, 12:47 PM
not an expert on this topic but do you have to preheat cast iron to keep it from warping? Thought I read that in one of my welding books.

lynnl
10-20-2006, 03:17 PM
YOD, I'm no expert either, but I think the preheating requirement is more applicable to actual welding, where you're generating much higher, more localized temps right at the vicinity of the weld. ...which tends to cause cracking in that high heat zone as it cools.

With brazing, since the heat is being applied more gradually, you are in essence preheating it anyway, PLUS the temps are not as high in any localized point. Which is why brazing is so often the method of choice for cast iron.

That's my take on it anyway.

Evan
10-20-2006, 03:21 PM
The only thing I question is making such a permanent modification to the machine. I really think long and hard before I make any "undoable" changes to my machines, at least the ones that matter like my SB. If I do make a change, and they are few such as my tailstock mod, I want it to look as though the factory did it.

loose nut
10-20-2006, 09:30 PM
you don't need to preheat but you should wrap the area around were you are going to braze with some type of fire proof insulation to keep the heat in and when you are done wrap it completely in insulation so it cools down slowly to prevent it from cracking, grind any sharp edges off on the parts that are to be brazed, these will overheat before the rest of the cast iron is at brazing heat and will "burn", after that you can't get the alloy to stick and you wuill have to clean it and start over. brazing steel is easy but cast iron can be tricky until you get the nack of it so practice on some scrap first.

John Stevenson
10-21-2006, 04:09 AM
The only thing I question is making such a permanent modification to the machine. I really think long and hard before I make any "undoable" changes to my machines, at least the ones that matter like my SB. If I do make a change, and they are few such as my tailstock mod, I want it to look as though the factory did it.
Why do we always assume that the factory got it right on the first attempt ?
Given constraints of time, design issues and ease of manufacturing they often cut corners.
Things like running direct in a casting instead of a replaceable bush or bearing, no oil seals fitted for ease of manufacture and cost.

Many often used common parts in their stores inventory instead of using a modified one that would have been more suited to the job.

I have modified many of my machines over the years to ease working, do a better job and be more reliable and to be honest if it changes the machine from what it looked like when new I couldn't care a rats arse.

It's a tool not a work of art.

Here's a classic example seeing as Evan has mentioned his lathe.
Here's one very similar to Evans from the lathes.co.uk site

http://www.lathes.co.uk/southbend/img7.gif

Boxfords in the UK took this design during the war and started to make clones.
This is one of the earliest post war models.

http://www.lathes.co.uk/boxford/img1.gif

I wouldn't imagine much of this later one would bolt onto Evans but I know which one I'd sooner own. That lever operated tailstock for a start is worth it's weight in gold.

.

malbenbut
10-21-2006, 04:34 AM
Knurl the steel part and push fit the cast pulley on should be strong enough for the small power that is to be transmitted
MBB

billyboy
10-21-2006, 11:01 AM
lets get this into propotion, i only put three little gas welding tacks on the two pulleys to be joined so it is not a perminent fixture, thanks for all advice given the job was successfull, the rerason for this modification is i do quite a lot of dovetail cutting and the speed rates of cutting feed are far too high with this miller in relation to motor output speed and cutter speed, i just need to slow the cut down so as not to damage either the cutters or the machine under power feed, i have tried all the speed rates under power and i just never got that lovelly cutting noise unless under manual power, hopefully i might of cracked it by doing this simple mod.

thanks

bill

Evan
10-21-2006, 11:32 AM
Why do we always assume that the factory got it right on the first attempt ?

I don't make that assumption John. However, the factory did get most things right on my lathe. The things that aren't there, aren't wrong, they are missing, such as the tailstock micrometer dial I made. There is a certain value to the machine being in it's original condition and I don't just mean monetary value.

Incidentally, my SB also has a lever operated tailstock. The wrench handle need only be swung from the right to the left and back to lock and unlock it. There is no need to remove and replace it.

John Stevenson
10-21-2006, 12:31 PM
No but if they got everything right why are there all these articles in ME, MEW, HSM and others with various mods ?

Billy is right about the feed on the Tom Senior being too high and it's not just related to that machine.
I have a Bridgy here with the mechanical power feed, slow is 9/16" per minute which is far too high for hogging in steel at a decent cut, so you are relegated to taking lighter cuts to save destroying cutters.

So if I alter this to slow the machine is that sacrilege ?

Last week I wanted to mill that curve in the back of that rack I made.
At first I thought I'd fit the horizontal head with a side and face cutter on a stub arbor but the size of the head is greater than the 4.25" that I wanted.

However whilst looking at this as I'd never used it before it states on the side:-
Fit to quill and tighten drawbar before tightening side clamp bolts.

OK that makes sense but this thing slides over the quill about 3" before the collet drive is home.
But where is the drawbar ? 3" down inside the vari speed head.
And yes it has the original drawbar with extended hexagon to suit the vari speed head.

So now I have to make a new extra length drawbar if I want to use this.

Will this detract from it's original value or will it add to it as it's more useable.

.

Your Old Dog
10-21-2006, 07:31 PM
Will this detract from it's original value or will it add to it as it's more useable.

That depends. You going to paint it Alistair Green?

I don't mind doing anything to my equipment that makes it more convienant to use now. I have no intention to leave it for somebody when I die and my wife sells it off to someone for $100 just to get it out of here. I'm not going to be leaving him a piece to sell to the Smithsonian Institution. I'm sure everything I have will go for 5cents on the dollar if that much. (If she only knew what I paid for it ! :D )

Millman
10-22-2006, 03:12 AM
Agree with John, things are made to be modified. Look how millions are spent everyday on automobiles; which are factory made. Haven't bought anything thaT COULDN'T BE IMPROVED. Computers....need to get a Bigger FH!

Evan
10-22-2006, 08:43 AM
I modify many of my tools. My Land Rover is a good example. I look at my lathe a bit differently. It's somewhat of a collector's item, at least for me. The same goes for my Unimat. As for what happens to it after I croak, well, that won't be my concern.

In a work environment such as John's the main thing is to make a living. If it needs to be improved then fly at it. We have been over this ground before.

rfrey
10-22-2006, 12:16 PM
So if I alter this to slow the machine is that sacrilege ?


I don't think you two are disagreeing (this time!) Evan only said he'd think long and hard before making a permanent alteration. I think that's pretty prudent. Factories do get things wrong, but if I have a machine with a factory feature, chances are I'm not the first one ever to see/use that feature. If we make a modification, we're into prototyping territory -- thus, either "think long and hard", or make it reversible.

Millman
10-22-2006, 12:23 PM
[[we're into prototyping territory ]] That's how ALL things were created.

TECHSHOP
10-24-2006, 12:27 AM
I fight the "must modify" gremlin, because once I open that can of worms, it always leads to more "while I'm here mods... ", until I have redesigned the entire machine. But the older and more complete the machine, the more I tend to "restoration" back to "factory new". If I purchased a tool new, and the warrenty is gone, then it is "whatever it takes" to make it work better is the rule. The most fun are "common stock" that has been "abused" and become the "raw material" for the next "grand project". All this, of course, has lead to a large collection of parts, very few functional machines, and no shop space to "safely" use them.