[LeeWay]

How much luck do you guys think I would have machining a weld?

I have to make some splitter mounting points for Powermatic 66 tablesaws. They are no longer offered by the parts houses or Powermatic. They are kind of odd parts. The real ones were M20 x 1.5 thread and had a hex head on one end. In the head in the center it has a hole tapped 3/8" 16.
The unit then has a lock nut so that when you have it screwed in in alignment with the blade, you lock it down to the trunnion casting. Then the splitter bolts on the head, which is a flat plane, using a 3/8" bolt.

I was going to use stainless, but decided against it. I bought uncoated steel threaded rod and zinc plated thin nuts. One nut becomes the head and another used as the locking nut. I would like to weld the nut to the rod and machine it flat in the mill. Then drill and tap.
The other option is to grind it or just put a few spots on the under side of the nut and not worry about how good it looks.
Thoughts, ideas, or been there done that. Don't try it?

[LeeWay]

Maybe if I anneal it before machining? That might crack the weld though. Hmm. May need to do some trial and error.

[SCzEngrgGroup]

Lee,

Hard to say. Some welds will machine ok, others will be hard as he11. Use carbide!

Regards,
Ray L.

[LeeWay]

Thanks, Ray.
That was pretty much what I found using google. I will try to machine it first depending on how good my welds look. I will be using a Lincoln 225 stick welder. I'll document the process.

My next issue will be applying some sort of finish. Kinda why I was looking at Stainless to start with.
I have zinc blackener here that I use for all the barrel bolts and screws on my guards. Does a nice job to blacken zinc plated parts. I don't think it does anything on raw steel, but I haven't actually tried it. My go to coating is typically powder coating, but because of the thing being mostly threads, that won't work.
So other than a heavy coat of oil, what other options are out there? I could powder coat just the head and the lock nut. That would be easy enough, but putting a finish on the threaded part is really the question.

[LeeWay]

I found this blackening kit at Caswell. I used to use the larger liquid cold app black oxide kits they sell. It worked okay.
For as few parts as I will need to make, this small gel kit might be just the thing. http://www.caswellplating.com/black-oxide-gel-kit.html
I think I will place an order and see how it goes.

[alan_3301]

If you do end up welding zinc plated nuts, make sure you do it outside with good ventilation.
Those things make some nasty fumes.

[LeeWay]

My welder is portable, but I usually weld right beside the plasma cutter. It's in an open ended garage and I use a couple fans to blow out the smoke. My other option there would be to machine a blank head out of flat bar and then weld that on the end.

The more I think about this, the less I am worried about a line showing between the nut and rod. As long as that is flat, I should get good results.
I can put three or 4 spot welds on the underside and be done with the welding. Then there is no chance of running a tap through any hard spots. That should work out well. It is not like there is any torque on these nuts when installed. All the torque applied will be to the center threaded hole and the lock nut itself. These so called thin nuts are still 10 MM thick. That is plenty of meat to machine away to a nice flat plane.

[kvom]

Just get some steel nuts. The zinc coated ones are a PITA. Grinding with a flap disk and angle grinder would likely look just fine and be a lot easier.

[LeeWay]

Just get some steel nuts. The zinc coated ones are a PITA. Grinding with a flap disk and angle grinder would likely look just fine and be a lot easier.

Now that is easier said than done.
These are fine thread metric nuts. My options are SS or zinc plated. I have searched all my usual suppliers.

I still have another option available to me with no welding. That is to peen the threads in a couple spots around the rod with a chisel and force the nut out to the end. Shade tree lock nut system. Then fill with red locktite. It would not be going anywhere.
That might be the best option yet.

[LeeWay]

This part will make me buy my first spiral flute tap. I typically use spiral point taps or gun taps. Not an issue because everything has been through holes. I may through bore this part too, but I think it is time to get a bottoming tap in the arsenal. About 2/3rds more on cost, but why not let a new product buy me some new tools.

A little history about these mounting points. I have probably turned away a dozen customers in the past because we could not locate this hardware. I currently have two guys on my waiting list that need these parts. I'm done turning so many away for such simple hardware.

[iwaskevin]

Lee if You pre heat and post heat and let the bolt cool slowly it should mach just fine. Lol I have a PM66

[LeeWay]

Thanks. Since you have a 66, you probably know the part I am trying to replicate.

[mactec54]

LeeWay

You are only welding mild steel, & most likely what you are using is made from free machining, this machines very easy when welded, how are you welding it, stick, tig, mig,or gas, any of these types of welding on mild steel, machining the weld very easy


iwaskevin no pre & post heat needed, it's only mild steel, you have to add carbon to harden mild steel, & even then it will only be a case harden, which you can still machine

[LeeWay]

Thanks for that too. I am using a Lincoln 225 Stick welder. I have a small wire feed welder, but I just use it on thin stuff like exhaust pipes and sheet metal.

[mactec54]

LeeWay

The mig ( wire feed ) would be best of the ( 2 ) if it has enough amps for the job, with a stick you have to be a good welder, because if you get any slag inclusion in the weld then the slag is what will kill your carbide when you machine it, you have to have a slag free weld, machining slag is like machining glass, the underneath metal is soft to machine, so make sure you have no slag in the weld before you machine it

[LeeWay]

So slag can flux up an end mill?
I weld pretty good with a stick. Not commercial good by any means, but I can make a pretty bead with the right rods.
The little wire feed is pretty light weight as far as penetration goes. That is why I only use it on thin material. It's an Italian made Shumacher.
It's an 80 amp gasless wire feed welder.

[mactec54]

So slag can flux up an end mill?

That's pretty much it,if your weld is clean, with no slag in the weld, or around it, then you will have no machining problems

[engnerdan]

Lee,
I had a welding business for about 5 years and have done many repairs that had to be machined afterwards. A couple things will weigh in on how hard it will be to machine but ultimately a carbide cutter should cut any mild steel weld.

1. Length of weld time and total heating of the part. Typically small tack welds and short welds on sizable parts where the weld heat is pulled out quickly will be harder. MIG or Stick weld tacks will be harder. A slow TIG weld tack will be a little softer.

2. Filler metal, the standard mild steel filler metal will be 702S-2 for tig, 70S-6 for Mig, and 7018 for stick. All of those are a 70,000PSI tensile strength metal. Your base metal if it is A36 hot rolled is only 36,000PSI so the weld will seem to be twice as hard. 1018 is about 53,700 PSI so a closer match but still favoring the weld.

If you do a post weld anneal (just heat the whole part red to yellow hot and slow cool) you will take some of the hardness out of the weld but the filler metal will still be nearly two times as strong as the base metal.

My advice is to weld it and use a 4-5 flute carbide cutter and use feeds and speeds for hard machining.

-Dan

[iwaskevin]

Lee it is to cold here in michigan to take the bolt out of my saw and measure it . are you sure it is 22 mm ? The pm66 saws were built in the us .mine is quite old it is green so they may have changed at some time. these were built for many years

[LeeWay]

Thanks for that info.
I think the older green ones may be SAE. Can't imagine a US company building with metric back then on US soil. The thread size came out of one of the parts manuals for a 66. Probably a newer one. I know they all have a 3/8-16" center hole.
I would think the thread size might be 7/8-14 or 20. Hopefully just 14. That is comparable in price to the metric stuff. The 20 is scarce and expensive. I will have to find out the exact thread at some point either with an old manual or when someone says this one doesn't fit.
Hopefully before that happens. I would like to get them the right size to start with.

PS, thanks for the advice, Dan. I had a stall on this project. My Son finally secured his first Home and that has been time consuming for him.
I am setting up a new Grizzly drum sander as well to sand some of our larger SS parts. I don't have a problem using an open belt sander on them, but he does. It is labor intensive though. We put a brushed finish on all those parts.
I'll keep you guys updated.