[CadRhino]

OK, I am ready to run my second part and have an old project that I was intending to do on my drill press but now that I have a Tormach I am thinking about running it to learn.

Here is the scenario, I have (40) sets of 1/4" thick x 4" x 4" angle I had water-jet cut for custom light bases. I had the waterjet cutter put (3) 1/8" pilot holes in random (but desired) locations on the face of each angle.

I was going to drill these holes to 3/8" diameter and then use a 11/32" bit to counter sink for a 5/16" Flat Head socket head cap screw.

I don't know how accurately the waterjet machine created the parts and pilot holes but since the same company makes part for Boeing, they should be pretty close.

Do folks think I should attempt to run all these through my Tormach? Maybe I could buy a stop to set up on my vise to try and get some good repeatability.

I am just a little nervous that if the pilots are not nuts on, the Tormach might have a hard time (and break bits).

Thanks for any thoughts/comments.

Best,
Nathan.

[RussMachine]

If you're worried that the 'pilot holes' from the waterjet aren't repeatable and accurate, then I would use an Endmill instead of a drill.
You said the parts are only 1/4" thick, correct?
I would use the endmill as a drill, and not worry about aligning the pilot holes. Peck drill it (G83) and go about .03 deep per peck.
Make sure you use a center-cutting Endmill (2-Flute works better).
You can also use the same tool to circle mill the counterbore for the socket head cap screw.
One tool should get the job done easily.

[Scott_M]

Hi Nathan
I have had some parts water cut in the past and was quite surprised at how accurate they were.
I would set up some sort of test fixture and measure a few of them to determine the accuracy of the pilot holes. If they are within your allowable spec. then just use a vise stop for repeatable part placement and drill and counter sink on the Tormach.

I would bet they are pretty darn close to what they should be.

Scott

[CadRhino]

Scott and Russ
Thank you for your feedback and insight.
I do not have a centering end mill but that sounds like something I should have. Russ, is there a mfg. or store you recommend I can find this?
Scott, that sounds like what I will do since I have the drill bits and parts on hand.
I have herd other folks on this site do just about energy thing on their Tormachs. I am just learning what that balance is in reference to the other tools I have ( lathe, drill press).
It is out of habit that I want to revert to one of my manual tools but I guess it is like learning a new language - you have to force yourself until you are fluent.
Thanks again.
Nathan

[bhurts]

Russ was recommending a center cutting endmill not centering. Most carbide and hss endmills under 3/4 inch are center cutting nowadays. You can look at them and tell. Look that the cutting face of the endmill has the cutting edge meet in the center of the diameter. If 4 flute then often only two of the four will meet in the center. If your not sure post a pic of the face of a endmill you have on hand and someone will let you know.

Ben

[Hirudin]

Although I can't remember having ever drilled a hole with an end mill intentionally, I think RussMachine has the right idea.

I'd be surprised if the water-jet cut holes are more than 10 thousandths of an inch (0.010") out of spec in relation to each other. Their relation to the edge of the angle might be a different story - I'm guessing that's what you're worried about. Using RussMachine's idea of just drilling them out using a center-cutting (AKA "normal") 3/8" end mill will take care of those worries, unless the water cutter is exceptionally sloppy.

Attachment 221448
Image source: HSMWorks

[GLCarlson]

To your other question. There are several tool supplier discussion threads here -a quick search will find them- but one consistently well rated supplier is Frank Mari at Maritool.

[CadRhino]

Thanks for everyone's input. I am learning quite a bit.
Russ, I see that your solution is actually the one I should probably do. I have HSS end-mill sets from Grizzly and Tormach. It turns out that the Tormach ones are center end-mills and the Grizzly ones look more like the non-center cutting ones.
I have both 2-flute and 4-flute but it sounds like you are recommending I use 2-flute. I guess that is because it might center better, right? I always thought 2-flutes were for aluminum and soft metals where more chip clearing was necessary and 4-flues were for steels. I will use the 2-flute.
Hirudin - thanks for the images.
Scott - You are correct on my concerns with the water-jet cut. The pilot holes were done on the opposite side that I will be drilling and counter-sinking. Water-jet cut holes are actually cones since the jet cannot do a perfect parallel cut like and end-mill/reamer/boring bar can do. This has me concerned that not only is the part to hole off but also the pilot holes on the back side are not perfectly located.
This is all the more reasons to use Russ' approach with the end-mill to just basically make new holes where I want them and then use the end-mill to make the counter-sink.
This is exciting stuff for me to learn.
I have read that the set-screw TTS holders are more rigid than the ER-20 holders so I will be using that. Sounds like I should be able to do everything with one 2-flute 3/8" center end-mill.
Thanks for the feedback.
-Nathan

[philbur]

As the holes are already cut you almost certainly could get away with a none centre cutting end-mill.

Phi

[Scott_M]

I think it would be faster to counter sink them with a counter sink. Trying to mill a tapered hole will take a long time if you have a short step or small scallop. Drilling with the end mill is fine but I would switch to a counter sink for the last op.

[CadRhino]

OK. Thanks Scott.

[RussMachine]

Are you CounterSINKING, or CounterBORING the holes?
There's a big difference.
Countersinking leaves a 60, 82, 90, 100, or 110 degree tapered recess for Flat Head Screws or Rivet heads. And, as Scott said, you will need to use 2 different tools to do that.
Counterboring will leave a flat pocket for Socket Head Cap Screws, and you could use one tool (endmill) to drill and circle-mill the pocket.

[CadRhino]

Hi Russ,

I am countersinking.
I wasn't sure if there was some kind of spiral code I could use for the 3/8" endmill to do both the hole and counter sink.
That being said, it sounds like should use the 3/8" center endmill to 'drill the' hole and then I will use a 11/16" 118 degree tip 2 flute drill-bit to do the countersinking.
I will work on some scrap parts and then do some 'pecking' to learn how to do that.
Thanks,
Nathan.

Are you CounterSINKING, or CounterBORING the holes?
There's a big difference.
Countersinking leaves a 60, 82, 90, 100, or 110 degree tapered recess for Flat Head Screws or Rivet heads. And, as Scott said, you will need to use 2 different tools to do that.
Counterboring will leave a flat pocket for Socket Head Cap Screws, and you could use one tool (endmill) to drill and circle-mill the pocket.

[philbur]

.....then I will use a 11/16" 118 degree tip 2 flute drill-bit to do the countersinking.

Wrong angle, Google countersink drill bit. Make sure you get the correct angle. The simple ones are very cheap.

Phil

[rowbare]

This is really a drill press job.

Sometimes the latest whiz bang machine isn't the best way for a particular job. I think this is one of those cases. Since the hole locations were determined in the previous process, it would be inefficient to try to do them on the CNC. If you only had one or two, doing them on the mill could be justified for practice but trying to do 40 would get old in a hurry.

I am curious as to why you didn't you have the waterjet people cut the holes to size. All you would have had left to do would be to countersink.

bob

[CadRhino]

This is really a drill press job.

Sometimes the latest whiz bang machine isn't the best way for a particular job. I think this is one of those cases. Since the hole locations were determined in the previous process, it would be inefficient to try to do them on the CNC. If you only had one or two, doing them on the mill could be justified for practice but trying to do 40 would get old in a hurry.

I am curious as to why you didn't you have the waterjet people cut the holes to size. All you would have had left to do would be to countersink.

bob

Hi Bob
You gave wise advice.
Thanks.
I didn't have the waterjet cutter do the full 3/8" holes because I thought it would be easier to countersink first then drill. That is what I did on the clients prototype.
At this point I may just finish them on the drill press but wanted to get my feet wet doing limited 'production' on my new Tormach.
Thanks again.
Nathan

[Spooq]

Something I have learnt the hard way - sometimes a CNC mill makes for a really crappy drill press