Zee Needs Popcorn

[Kim]

Well today went relatively well...no doubt due to the loads of good advice I got.

No doubt! 

1) Each time I drilled I could tell the brass was trying to pull the drill bit out of the tail stock. It helped if I fed a little faster but I didn't like doing that. That kind of tells me that the idea of having brass only bits may be a good idea.

Or, that you were doing the right thing - feeding it in in a controlled way like this made it so the bit couldn't grab. Or, that when it tried to grab, it was held in place and not allowed to do the evil it wanted to.  I'd call that a win!

2) At one point, with a larger drill bit, the system stalled. I was running about 300 RPM with a drill bit about 7/16 or slightly less. I think the speed was too low or my system can't provide the torque at that setting.

Maybe.  Or maybe you were feeding in too fast and trying to carve off more metal than you had power to actually do?  Just a thought... I'm assuming you backed out and fed it in again, a little more slowly after that?

I had squared the stock on the mill then went to the lathe. One would think (or I had thought) that if the stock was perfectly square then a facing operation of 1 thou would take 1 thou off the entire face. Not so. It took about 5 or 6 thou before the entire thing was faced. It was slightly worse when I flipped the part and face the other end.

I had squared the stock using a 3/4" end mill and was pleased to see the expected pattern of a trammed machine...in the X direction.
But I believe, the Y is off. By some significant amount given the size of the part is at most 1.375".

However, I'll be interested in anyone's thoughts on similar findings.

Hmm... It does seem like something was out of square.  If the part was squared up when you started, and the machine is square, then I would expect that you'd take a nice skim off the end, as you said.

Is it possible that your block wasn't mounted squarely in the chuck?  Or that the jaws of the chuck aren't square with the Z-axis of the lathe?

If you can't tell...I'm somewhat chuffed (as they say).

As well you should be!

One thing that bothers me...When I look at the end where the reaming started...it looks pretty decent. But at the other end I see a little grooving as if the boring bar was wider there and the reamer did nothing.

Or maybe, the reamer got full of chips toward the end of the bore and that's what caused those gouges?
Just a thought, I don't really know.

Also, did you use some cutting oil for the reaming operation?  I've found that helps a lot.

Foo. Maybe not so chuffed. Makes me think the tail stock is not in line.

I'd still be chuffed!  It's good progress and WAY better than the first one, right?
The way I look at it is, I've got to leave room for me to do something better next time!  If it were perfect, where would I improve?

I feel good and that's what matters.

Yup, that's what matters!

Looking good, Zee!
Kim

[Brian Rupnow]

There is no real guarantee that when you clamp something in the chuck jaws that it is going to be perfectly aligned on the rotational axis of the spindle. Seems weird, I know but that's the way it is. If you knew the face setting against the chuck was "square", a good practice is to tighten the chuck about 3/4 of what you normally would, then smack the exposed face with a dead blow hammer to seat the opposite end tight against the chuck face, then re-insert the chuck key and give it that last final grunt before you start machining.---Brian

[john mills]

speed  for 7/16 drill machinery hand book has 120    140 f p m  that is 1200 rpm so 300 is very slow.
for 7 /16 you should go strait in  taking only a 1/16"in dia the drill will want to grab dig in as you have found it
the metal in the centre of the hole helps hold the drill and you have to feed it in.and the flat can help but for a small step in size will be difficult to control .  The marks after reaming is the swaff the flutes will be full and begin
to tear ,oil helps but i would not try to take  1/64"on dia with a reamer on a 1/2" hole bore closer to the size.

[Jo]

One last observation...which bothers me a bit...

I had squared the stock on the mill then went to the lathe. One would think (or I had thought) that if the stock was perfectly square then a facing operation of 1 thou would take 1 thou off the entire face. Not so. It took about 5 or 6 thou before the entire thing was faced. It was slightly worse when I flipped the part and face the other end.

I had squared the stock using a 3/4" end mill and was pleased to see the expected pattern of a trammed machine...in the X direction.
But I believe, the Y is off. By some significant amount given the size of the part is at most 1.375".

However, I'll be interested in anyone's thoughts on similar findings.

Zee don't beat yourself up over this. In the future try to always face and bore a cylinder from the end that the piston rod goes in, while the cylinder is still mounted. That way you know that the piston and piston rod will be square to the bore. The other end doesn't matter if it is slightly out  But you can true the other end up by holding the cylinder on a mandrel in the bore.

With a cylinder your reference to which everything else must be taken is the bore 

Jo

[zeeprogrammer]

Thanks everyone.

A couple of people mentioned the use of oil. I've had the understanding that oil is not used when machining brass. Are there certain operations with brass where oil is recommended?

I understood the bore is the reference and the (new) face is square to it. My comment was about the new face now not being square to the plane that sits on top of the pedestal. So when I mount the cylinder it may be tilted. Had I realized that may happen, I would have waited to finish that plane to dimension (using the bore as dimension). It may be that it will be close enough and if not then I can machine that plane to be true to the bore and remake the pedestal to get to the required height.

1200 rpm? Unless I move the belt, the lathe can't get there. Don't smaller diameter drills require even higher speeds? For boring I just set the speed until it feels/sounds right. Too high always seems to give me trouble. For reaming I also go slow.

[mklotz]

...
1) Each time I drilled I could tell the brass was trying to pull the drill bit out of the tail stock. It helped if I fed a little faster but I didn't like doing that. That kind of tells me that the idea of having brass only bits may be a good idea.
...

Some idle thoughts on the matter of a set of brass drills...

Since they'll only be used on a soft metal, they don't have to be high quality steel.

Since their primary use will be bulk removal of material rather than precision hole sizing, they don't need to be highly accurate as to size.

Given the previous statement, you probably get away with not having letter or number size brass drills.  Use the closest fractional; you're going to bore/ream after drilling anyway.

Since you're going to intentionally dull them, they don't need to be well sharpened.

Harbor Freight sells a 29 piece fractional drill set (#62281) for $18.  It's actually decent.  I have one in my house repair tool carrier and it's held up well.  I wouldn't use them for precision work, I have high quality drills for that, but for household tasks they're fine.

So, my thinking is spend $18 for drills and maybe an hour or so putting a flat on the cutting edges and you're armed for most brass bulk removal tasks.

I haven't done this myself.  Using the fine feed works well for me for controlling drill grab in brass.

Another option for bulk removal is "drilling" with an end mill.  However, keeping an array of endmill sizes to match the fractional drills would get very expensive.  I think the drills are a better solution.

[john mills]

smaller drills do like higher speeds but you can only use  the speeds you have. slow speeds for reaming is good.
A little oil on the reamer will help the swag not to scratch the fished surface.But best not to let the flutes fill with swaf. I have worked on cnc machines that would fit 400 mm dia and do 3600rpm and used coolant on metal bronze brass and white metal but cut teflon material dry.Bronze cut at 300 mph.The machine is closed in with the door shut even the swaf coming off needs to be closed in.  but you can't use sufficient coolant on your manual machine with out getting wet and making a mess so it is better dry.and at the speeds you can use its ok dry .if you can, coolant is good to use.

[steamer]

...
1) Each time I drilled I could tell the brass was trying to pull the drill bit out of the tail stock. It helped if I fed a little faster but I didn't like doing that. That kind of tells me that the idea of having brass only bits may be a good idea.
...

Some idle thoughts on the matter of a set of brass drills...

Since they'll only be used on a soft metal, they don't have to be high quality steel.

Since their primary use will be bulk removal of material rather than precision hole sizing, they don't need to be highly accurate as to size.

Given the previous statement, you probably get away with not having letter or number size brass drills.  Use the closest fractional; you're going to bore/ream after drilling anyway.

Since you're going to intentionally dull them, they don't need to be well sharpened.

Harbor Freight sells a 29 piece fractional drill set (#62281) for $18.  It's actually decent.  I have one in my house repair tool carrier and it's held up well.  I wouldn't use them for precision work, I have high quality drills for that, but for household tasks they're fine.

So, my thinking is spend $18 for drills and maybe an hour or so putting a flat on the cutting edges and you're armed for most brass bulk removal tasks.

I haven't done this myself.  Using the fine feed works well for me for controlling drill grab in brass.

Another option for bulk removal is "drilling" with an end mill.  However, keeping an array of endmill sizes to match the fractional drills would get very expensive.  I think the drills are a better solution.

Excellent points Marv.   If you've never cut brass with a drill ground like this...you're missing out...it's SO much easier to deal with.

Dave

[zeeprogrammer]

Was working on the (new) cylinder (again). 
Busted a bit. 
Cleaned shop. 
Taking it easy. 
Will be back. 

Ideas on getting that bit of bit out are welcome.   

[crueby]

How big a bit how deep in, what is showing, assume into brass? Twist drill?

[Stuart]

Zee

Did it squeal, if so it may have chip packed

[zeeprogrammer]

Thanks guys.
Brass and twist drill.

I was drilling from one side of the cylinder to the other, through the exhaust port.
When the bit hit the exhaust port is when things went awry.
Looking back on it...it was very dumb.
The geometry was such that when the bit got to the port, it would be like drilling into half a hole.

In any case, this morning I lucked out. Apparently about an 1/8" of the bit was stuck at the very edge of the port but was shattered and I was able to pick it out.

I can continue my march of one step forward and two steps back.

[Tennessee Whiskey]

You can’t beat lucky. You brought up a great point of discussion on reaming the cylinder. I have heard many times to not “peck ream”, but, to poke it through in one go. However, I wonder at our ratio of depth vs. diameter, if it’s not best. In other words; clear the swarf. When your lathe stalled; did the motor quit or the belt slip?  I usually start with anywhere from a 1/16 to a 1/4” pilot hole and then either shoot straight to hole size or step up in half increments. I am happy to see you “climb back on the horse that threw you”. We’re getting there 

Cletus

[crueby]

Zee, when drilling are you using the side handle, drill press style?  As others mentioned, using the fine feed is much better on starting and breaking through, much finer control, no where near as much tendency to grab the new edge and pull forward like a coarse screw. I have much better luck drilling through on my sherline mill, with its vert screw feed, than on my drill peess with the side handles. Its slower, but better.

[zeeprogrammer]

Thanks.

@Cletus...I fell off the horse again. See below.
@Chris...I was using fine feed but because I had forgotten the port was there...I fed too fast.

Today was the usual story. Got the ports done, the holes drilled and tapped for the covers, the ports from the bore to the inlets, and the exhaust.
Just needed to trim away a bit and then the last operation was going to be milling the curve.
I was happy.
The usual story is the last, or 2nd to last operation goes to poo.
I became unhappy.

Took too much of a chunk when trimming and the part flew out of the vise with horrible marks along the face where a cover will be.
I went ahead and finished trimming. I'm hoping most of the marks will be carved away when I do the curve or hidden by the cover.

Bad story gets worse. I realized the face I made square to the bore isn't the one where the piston rod goes through.
I tried to see if it was okay...chucked it up in the 4-jaw, put a shaft in the bore and measured.
Looked cruddy but I'm not sure why.
I will wait and see how it goes. Could have been a bad chucking job...or nothing about my machine is square.

Tomorrow I will do the last operation (carving the curve) and set the thing aside.
If I have to do it over yet again...I don't want to do it now. It's been frustrating.

As is my habit...I look for the silver lining. This is only the 2nd attempt. 3rd time is charm. Beyond that...I may sell my machines.