I am not a machinist...

[cgruhlke]

Hello everyone. I'm new here this is my first post. I apologize in advance for the extremely simple nature of the questions I am about to ask. I am a Mechanical Engineering Technologist so I have some understanding of general machine work and have taken a couple of courses on the topic, but have never done anything that would be considered serious machine work.

I'm working on a small project in which I have to make a smallish quantity of mild steel spacers. They vary in size from a little over 1.0" to about 2.5" in length with OD's of 3/4", 7/8" and 1", and ID's of 23/32", 51/64"...you get the picture. These are very simple crush sleeves for an automotive application and I have a total of about 250 to make. I have access to a very old, and sort of worn out lathe at work. The tolerances of my parts are very loose and I don't need great finishes so I feel confident that I can do this myself. The lathe has plenty of horsepower and I have a pretty good selection of tooling.

Let me use an example part to pose my questions...I have a sleeve which is 1"OD, 51/64" ID and 2.20" in length. My plan is to turn the OD from 1-1/8" C1018 round stock. Then using taper shank drills, drill the ID in steps. Then part the piece and Bob's your uncle. I do not have a small enough boring bar so I have to use drills. This is the worst case of my parts with the largest ID.

Questions: How many steps to drill to 51/64"? Can I drill the ID with out flooding coolant, just using a liberal dose of cutting fluid? Can I turn the OD without flooding coolant using HSS tools?

Any advice you have to offer would be welcome. If anyone local wants to help a brother out I would accept gratefully.

Thanks for your time.
Charlie.

[dertsap]

cutting oil would be sufficient for turning and drilling , if its not at hand then you can use a substitute such as motor oil veg oil or what have you

[Eurisko]

If you have some end mills available, I'd try this sequence...

center drill
5/8 drill
3/4 end mill
51/64 drill (or reamer)

A conservative 4 steps would be a good way to start.

[MrWild]

You really don't need to run that many steps. Look at the middle web of your largest drill. All you need is to drill a hole 1.5x that web width. If the web is 1/8", then a 1/4" pilot hole is sufficient. A center drill, then the pilot hole, and finish with the size drill. I really wouldn't use much over 3/8: for a pilot hole to be honest. Doing too many steps is a great way to court chatter and bad finish. As you have enough power, you don't need to take baby steps. Doing multiple steps is for weak under powered machines. With 250 of these spacers to make, the fewer steps making them, the better off you are.

[PixMan]

For a hole that size, you likely don't need any drilling steps at all. If the machine has a 3HP motor or better, just get a split-point drill and do it. Start the hole with a 3/8" or 1/2" 120 degree spot drill and git 'r done.

I used to do a lot of big holes. That size was always a one-shot deal. Anything bigger than about an inch, I just used a spade drill and dispensed with the spotter. Don't use a "center drill" (a.k.a. combined center drill), the tips aren't needed unless you're going to be turning between centers for the O.D. Moreover, those things don't really center a drill all that well because of the 60 degree angle. A spotter is made for the job.

What kind of lathe do you have to work with anyhow? An old South Bend 9" would need starter holes, but if it's a decent Clausining, LeBlonde, Mori Seiki, etc...no problem.

[John Welden]

I'd sub the job out because it's going to take you forever to do all that drilling. You will be there for days. If you spend 10 minutes on each part, that is about 40 hours of work.

Without flood coolant/oil and a good way to peck the drill, you're going to toast your drills with so many parts to make. If your only way to feed the drill is with a conventional tail stock, that is a hell of a lot of cranking back and forth.

I don't see why your company would want to pay you to do the job of machinist. Waste of money. You are going to be miserable doing this job yourself.

If you must do it yourself, you should post pictures of what tools you've got to work with. From there, you can get advice on exactly what you should do to make the job as easy as possible.