Help...drilling 1/16 hole in brass 60XD

[Fretless]

I'm drilling .5 deep with a stub drill and following up with

mid hangout (3.0) aircraft drill to drill 2.75 deep

and then a long hangout aircraft drill to go 3.5dp.

 

start the drill @ 500 rpm feed into pilot hole ramp up rpm to 3056 , coolant on and continue with drill cycle.

the drill broke during the deep part of the hole.

 

run out is .0007 @ collet. and a few thou at tip.

 

The challenges are "no" coolant thru, VMC, & Cleveland twist aircraft drill as only option.

wall thickness is .033 and the holes intersect an the bottom.

currently running 50 sfm, .01 peck  feed is .001 per rev.

 

 

how would you improve this operation?

[Mr. M]

Start with the runout. Make sure that the first drill leaves a straight hole also or that will cause issues.

[crazy^millman]

Need to get that run out down to .0002 at the tip. Need the correct drill trying to use that wrong drill is going to keep ending badly. Parabolic polished drill will be your friend here. Long drill should not start until in the hole and should stop before coming out of the hole. Might try some mineral spirits or kerosene. SFM seems might slow for brass, but depending on the grade need to watch for it being gummy. G83 in the hole and work on the peck depth. Other than that 60D is not easy.

 

HTH

[Fretless]

Thank you Mr. M, I will improve the run out and check the straightness of the hole. 

[Fretless]

I agree Ron, getting the run out is critical to the success of this operation. 

The indicator spring is stronger than the flex of the drill tip. I don't have an optical tool pre-setter.

I will increase the sfm. back up to 80 and change the entry and exit of the long drill.

a polished parabolic, mineral spirits and kerosene are not an option at this time.

How would you address the peck amount?

What do you think about the feed per rev?

[Rstewart]

I think you may be a touch high on the Feed per rev (For That long of a drill).

[crazy^millman]

Sorry to say you in in for a fight then. Baby it baby it and baby it.

 

Reminds me of being a kid and have to dig a ditch with a shovel. Owner had a backhoe, but didn't want to spend the money on the fuel to run it. 1 week I dug away and he was not happy about my progress. He left early one day and my dad brought over 20 gallons of fuel. I fished everything that needed to be done in about 2 hours with the back hoe. I think it would have been another 3 weeks of digging. Showed up the next day and the owner was upset I was done. He said it was that was not the point. I told him pay me for the work and the gas and have a nice day. Penny wise and $100 dumb gets you a fight. Techonology is there to do the work, sorry for whatever reason you are stuck using a shovel to do the work of a backhoe.

 

I did that many times while working shops. I bought the tools got the job done they way it was supposed to be done and gave the owner the receipt for the tools when I was done.

[Fretless]

this worked,

pilot drill .0625 dia. run out .0002 .5 deep.

.0625 air craft drill hang 3.46 to drill 3.415.

run out was .0001 at collet and .0005 at tip.

G04 entry, increased sfm to 80.

and decreased fpr to .0005. peck .01

eliminated mid length aircraft drill.

Thank you, Ron, & Rstewart for your help.

[crazy^millman]

Glad you sorted it out.

[AMCNitro]

Had to make some electrodes on copper last year on something of similar depth, but the drills were .046 IIRC.  And I was doing them on a manual, the smaller the peck the better.  Something I've used for years is Tap Magic...