Machinists, anyone ever make a push broach?

[lil_Blue_Ford]

So, I’m not sure I’m really much of a machinist with never having run a CNC, mill or lathe. I do have a couple basic machinist and blacksmithing books though and I have a grasp of the basics to a minor degree.

That said, I have a problem that I think can be solved with a push broach or whatever you want to call it. I bought a replacement stump jumper for my brush hog awhile back and it doesn’t exactly fit. It has tapered groves for splines on the shaft to fit in like this \_/ and the problem is they are too narrow. A family friend took it to two of the machinists he knows and neither was able to solve the problem. I don’t see why one couldn’t fashion a push broach and holder and just scrape the grooves wider one at a time. There’s 12 grooves to widen and I want to say it’s a 1.25” hole in the middle of them.

I’ve never attempted anything like this however, so I’m looking for some input, otherwise I’m just going to take my best guess based on my limited knowledge and hope for the best.

 

[franklin2]

First thing to do is take a file and run it over the splined area. Nothing dramatic, you do not have to push very hard, but see if it wants to cut the splines, or is the file just vibrating over the splines and not doing anything. If it's not wanted to cut, then the splines are hardened and any modifications will have to be done with a grinder or stone of some sort.

 

[lil_Blue_Ford]

First thing to do is take a file and run it over the splined area. Nothing dramatic, you do not have to push very hard, but see if it wants to cut the splines, or is the file just vibrating over the splines and not doing anything. If it's not wanted to cut, then the splines are hardened and any modifications will have to be done with a grinder or stone of some sort.

It’s powder coated and the file doesn’t seem to like that, which I think is a decent part of my problem

 

[pjtoledo]

how 'bout a pic?
splines on the male or female need enlarged?

for enlarging a hole you would want a tight fitting stud with only 1 groove and rotate it. grind a tool bit to fit the groove.
the hardness of the splines will complicate things. hardened parts can be softened by annealing, then machined, then re-hardened.

disclaimer, I'm not a hard core machinist.
try these guys:
hobby-machinist.com

 

[85_Ranger4x4]

It’s powder coated and the file doesn’t seem to like that, which I think is a decent part of my problem

Wire wheel the powdercoat away before you do anything. Nothing will like dealing with that crap.

Then try a file or whatever, decent chance the shaft will be at least surface hardened though.

 

[lil_Blue_Ford]

how 'bout a pic?
splines on the male or female need enlarged?

for enlarging a hole you would want a tight fitting stud with only 1 groove and rotate it. grind a tool bit to fit the groove.
the hardness of the splines will complicate things. hardened parts can be softened by annealing, then machined, then re-hardened.

disclaimer, I'm not a hard core machinist.
try these guys:
hobby-machinist.com

I’ll get some pics today. Been fighting a cold or something and the past couple days have been freezing cold out so I’ve been putting off going down to the shop. Today it’s supposed to hit almost 50* and I’m doing better so I’ll get back after it.

I was going to leave the splines on the shaft alone unless it would be better/easier to modify those. Those are male splines and easy to get at, but my thought was to modify the more easily replaceable part.

The stump jumper is female splines and they don’t need to be deeper, but rather wider. The complicating part is that the spline sides are sloped.

I’ll also sketch up what I was thinking about making for tooling and get a pic of that

 

[85_Ranger4x4]

Same number of splines?

 

[lil_Blue_Ford]

Wire wheel the powdercoat away before you do anything. Nothing will like dealing with that crap.

Then try a file or whatever, decent chance the shaft will be at least surface hardened though.

I haven’t been able to figure out a way to wire wheel female splines in a hole…

 

[lil_Blue_Ford]

Same number of splines?

12 splines on the shaft, 12 splines on the stump jumper. I took some preliminary measurements awhile ago, I’ll see if I can find those to show the difference, if not, I’ll take another picture, they should be on the one white board down my shop still

 

[lil_Blue_Ford]

See if that makes sense… probably not, I know what I measured, but I’m not exactly sure how to describe it other than doing a short video or something

 

[85_Ranger4x4]

Is that with the powdercoat still on the splines?

Get rid of that before you do anything, it can be rather thick on its own.

 

[lil_Blue_Ford]

Is that with the powdercoat still on the splines?

Get rid of that before you do anything, it can be rather thick on its own.

That is with the powder coat. I’m not quite sure how best to get rid of it, wish they wouldn’t have done that but here we are. Been tempted to hit it with my torch and see if I can melt/burn it off. Not sure how else to get rid of it other than pushing a broach through to cut it off.

 

[85_Ranger4x4]

That is with the powder coat. I’m not quite sure how best to get rid of it, wish they wouldn’t have done that but here we are. Been tempted to hit it with my torch and see if I can melt/burn it off. Not sure how else to get rid of it other than pushing a broach through to cut it off.

Wire wheel on an angle grinder is the best I found when I was stripping a old grille guard.

Paint remover won't touch it.

Everybody thinks I am crazy for hating the stuff but it is a nightmare to deal with.

 

[RobbieD]

I haven’t been able to figure out a way to wire wheel female splines in a hole…

Rig a bore brush into a jigsaw maybe?

 

[Shran]

Burn it out with a torch. I hate powder coat too, it has its applications but paint is almost always better.