How would you make this? Out of Steel

[JWB_Machining]

How would you make this? I know I should turn down a 2 inch bar and then cut it on my band saw but where do you think I should go from there? Any suggestions welcome.

[Geof]

That is a nice challenge; how many are you doing?

For making lots I would start as you suggest with round bar the correct diameter for the curved side.

1st Operation would be to grip in custom vise jaws on the ends to machine the flat side leaving the ends which get the tab and taper unmachined.

2nd and 3rd Operations would be on a rotary fixture with the machined pieces held in a custom clamp (on edge) leaving the ends available to finish machine them both.

For a one-off I would still do the flat first but I would probably clamp the ends in Vee blocks.

The two ends would be done in a standard vise with it being flipped once to get the second side of the tab.

You do not specify any tolerances; if you want it parallel to +/-0.0002" over the length you are going to have to fiddle a bit.

[JWB_Machining]

Tolarances thankfully are +/- .020 and I've got to make three. I'm afraid after I face the flat part I can't take it out of the vise or it'll be a pain to get it lieing flat again, I could use a level but idk. I'm thinking set my vise on a swivel angle plate, vise down on the two ends of the bar, then face down a large enough portion, angle it one way to get the side chamfer, unclamp the vise, turn it 180 then to the other chamfer. From there idk, I think I'll make this in Wax once or twice to get it right I'm just hoping someone has some magically easy answer.

[Geof]

Originally Posted by JWB_Machining ...I'm afraid after I face the flat part I can't take it out of the vise or it'll be a pain to get it lieing flat again,....

Mine is the magical easy answer.

You do not need to get a lying flat again.

Grip it on the ends with packing in a single vise if it is short enough to fit across; use two vises or Vee blocka as I suggested if it is to long for a single vise.

Machine the flat side extending slightly past where the tab comes to on that end and slightly past where the taper comes to on the other.

Now grip it in the vise with the flat side against the fixed jaw; you may need a piece of parallel packing for this. If you have a good vise the fixed jaw face is going to be aligned with the Z axis to within less than 0.001.

Now machine the taper using maybe a 5/8" cutter with at least a 2" length of cut.

Go to the other end and machine the tab profile, face of the side that is accessible and do the hole.

Flip it end for end in the vise and machine the other side of the tab.

[JWB_Machining]

I Like that, that Sounds not nearly as painful as I originally though. The only thing is that there needs to be a 1/16 radius where the tab connects with the rest of the part. So maybe after facing it use a 1/8 drill to create the two radii and then I can flip it on it's side and just step over once I reach the right depth so as not to nic the radii? Also do you think using soft jaws would be advised so incase i'm off a little bit I don't hit my valuable jaws?

[JWB_Machining]

Oh, One other thing I was curious about, The part need to be .5 thick, when i'm face milling it down how can I measure this? I was thinking probe the base of my vise and just making sure my final pass is .5 above that.

[Geof]

Didn't notice the radius. Just use an end mill with a 0.06" corner radius for milling the sides of the tab.

For getting the thickness if you start with something 2.000" diameter, touch off on the top and go down 1.500" you have your thickness.

Soft jaws are a good idea when you are getting into tight spaces.

Some parts do look a bit daunting at first glance, maybe when you have nearly forty years experience you will see one or more alternate approaches almost straight away.

[JWB_Machining]

I see you your idea for gettin the thickness but is really milling down 1.5" that feasible? I was going to take the 2" bar and cut it down it's length on the band saw so I could get 2 per length of bar, so any suggestions then?

[Geof]

Incidentally what type of steel or do you have flexibility?

If you took a length of cold finished round bar and machined three quarters of it away it will distort; it is difficult to predict which way but my guess is that the flat side would go concave. probably it would still be within your .02" tolerance but it might look bad and the flat side would certainly not sit flat on straight surface.

The best material would be hot rolled if a mild steel is okay and annealed stock if you are using an alloy steel such as 4340. If someone is asking for it to be made from C1045 ground shafting good luck.

[JWB_Machining]

Well the Material Selection isn't really all that important, it actually came down to me rummaging through stock till i found something that was a workable size, it tested Rockwell B 95 (100 ksi Tensile) I did have a piece of 4340 but it wasn't long enough to get 3 out of. But yeah if I did mill down a whole 1.5" and it didn't sit flat on a surface that'd be fine, I just think that would kind of be time intensive.

The objective of these spike is to stand up next to eachother in a circle so that they can be plunged into the ground below asphalt that has a approx 2" hole drilled in it. Then they take a pipe and force it down on the chamfered/tapered ends so that the spread out like an anchor so that when they're pulled on they'll grab the asphalt and stay put, I think they're aiming to hold 15,000 lbs to stop a car or something. So really my tolerances are loose and they just have to fold up n fit within a 2" hole but I'm trying to stay in tolerances n become a better machinist since this is one of my first few money earning jobs.

[JWB_Machining]

Oh one last thing before I leave for the day. Someone, i think you may have told me that my depth of cut should be 20% of diam or less for under 5/8 so If i'm using a 1/8 ball end mill my depth of cut should be .025-.02 And I was told my IPT should be 0.5% of my diam so .000625 IPT?

[langwadt]

I'm not a machinist I don't even play one on tv, but..

how about four pieces of flat bar of about the right width and thinkness held around a square "core" turn down the outside and take it apart and you have four pieces flat one side round on the other