Info re: machine shop rules/methods


#1

Woodworker primarily, but need to do a little with that extra hard iron wood! Seriously, I need to cut a 1.5" diameter cold roll steel bar into nine pieces 6" or less in length and then tap one end of each for a 3/8" bolt. Do any of the DMS tools I will need require special training?

Wouldn’t mind at all having a pro look over my shoulder for the first one to be sure I am doing this correctly and efficiently. Can be there before or after tonight’s board meeting as well as most of Tuesday before 7 pm.

@Team_Machine_Shop


#2

You’re over on the machining side of the world now.

What king of tolerances do you need? +/- an inch? a tenth? a thou? tenth thou?

If you need “no” accuracy, the cold cut saw could be what you want, but I’m not sure how well round stock would clamp in it.

The band saw would be another “no” accuracy tool, and probably the best bet.

If you want to do it the most “fun” way and have as much accuracy as you want, then I have a lathe class Wednesday evening here: https://calendar.dallasmakerspace.org/events/view/10824

In any case, spot train on the bandsaw or the cold cut, or come to the class on the lathe. I can’t think of a safe non-trained way to cut something like that.


#3

How accurate do the pieces need to be? The horizontal bandsaw has significant deviation in the cut, however with 1.5" stock, it would barely be visible to the untrained eye. Otherwise, the cold cut saw (training required) would make quick work of the problem.

The drill press is the easiest way to make holes, with the end mill being vastly more accurate.


#4

As they say, many ways to skin the cat, some more accurate than others. Machinists usually just go with whatever they’re most comfortable with that gets the job done.

With zero accuracy required, he could cut them off with a reciprocating saw and a metal blade. :grinning:


#5

The only part requiring accuracy is the thread tapping. Cutting approximately to length is good enough.

Horizontal band saw was my guess and something I’ve done outside DMS.


#6

The cold saw is probably the way to go but has a quick 10 min training. The lathe might be the way to center drill it accurately. It can then be tapped using the spring loaded live center on the drill press. Unfortunately I’m not available tonight


#7

To cut this part I would rough cut it on the band saw or the cold cut saw then drill and power tap it on the lathe.

The lathe does require training, as does the cold cut saw.


#8

I assume the hole is drilled along the axis of the rod, like pins for a floating shelf.

IMHO the holes are best drilled on the lathe, and most lathe teachers will do the training on the cold cut saw so you’d be good to go. This probably requires the most training effort however.

The band saw and drill press are the other ways to go, the band saw probably won’t make a square cut (no miter gauge iirc), and it usually doesn’t have a particularly sharp blade, but it’s an easier training than the cold saw and doesn’t have the blade breakage fee if that’s a concern.

The drill press would require finding the center of the bar, clamping it securely in the vice (vblock probably) but otherwise doesn’t require specific training. I have a personal dislike of our drill press (loud, mostly, it might have some runout), but that’s just me.

The only horizontal bandsaw we have is in metalshop and I’m not sure if we have a controlled downfeed on it…


#9

Get the training on the cold saw. With the cold saw all the cutting will only run minutes. You better pack a lunch and a dinner if you want to cut that much steel on the band saw.
( If the blade is sharp it can be fast, but probably would stay sharp to the end of that much cutting)

Get trained on the metal lathe. Use it to face off the rough cut ends to be perfectly perpendicular to the cylinders and to drill the ends for the tap operation. Consider drilling slightly oversized holes to ease tap turning and reduce the possibility of tap snap off. ( luckily the bigger taps don’t snap off frequently like the small taps) A few mil diameter extra does not lower pull out force much.
Tap each hole while the piece is still in the lathe chuck using a tap guide in the tail stock drill chuck to perform an aligned tap. Still hand tapping, not power tapping.


#10

I’ll be around this evening and can give you the cold cut training. Whilst there may not be enough time for a lathe class I don’t mind helping get them faced and drilled.

Cheers,
-Jim


#11

You got it! After the meeting or before?
BTW, I am the Bert you met in the shop last night.


#12

Probably after; when you see me around feel free to grab me. The cold cut training takes about 5-10 min and after you cut those down we can get to the drilling.

-Jim


#13

Cold Cut saw will cut material - training required. Get with anyone who is trained and they can train you.

Need to use lathe to bore hole for taping, or could be done on Bridgeport … bother need training. You COULD drill hole on drill press, but probably have issues with it being true and perpendicular.

Look up hole diameter for .375" thread (based on type of thread). Verify we have that type/size tap and drill. A tapered tap works best, then can use bottom tap to finish hole if you need it all the way to bottom. If the bolt isn’t going to be under much load, you may consider drilling the hole slightly larger than the recommended size - makes it easier to thread and less likely to snap and tap.

[quote=“malcolmputer, post:2, topic:52508”]
I’m not sure how well round stock would clamp in it.
[/quote] Will clamp just fine.

As to accuracy, you should be able to get within .015" if careful. If you use a stop, you can get them all cut to within .015" in length of same size at least.


#14

Thanks for the feedback. John helped me cut three pieces to test my project concept. Was able to go low tech: cold saw, drill press, found a way around having to tap threads. All to basic carpenter’s standards versus the habitat of the machinists. To you guys, it’s fine rolled steel with precision tolerances … to me it’s an unusually symmetrical chunk of really hard wood!