Super thin titanium rudder blades.

[Andy Brown]

Nice job Terry!

 

[Brad Christy]

Jim,

Are you referring to standard 135 deg split point drills, or something altogether different? I've always used these drills for Ti if I can't get ahold of carbide, but if there's something better, I'm all ears.

Terry,

Moly-Dee is your friend. It stinks, but it works wonders.....

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC

 

[Blackout]

Awesome Terry!

 

[Jim Allen]

Jim,

Are you referring to standard 135 deg split point drills, or something altogether different? I've always used these drills for Ti if I can't get ahold of carbide, but if there's something better, I'm all ears.

Terry,

Moly-Dee is your friend. It stinks, but it works wonders.....

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC

There are two types of faceted drill points that could be used to drill Titanium. These type points cut from the center in the same fashion as any split point drill & therefore they do not require center drilling to start the drill. However, the faceted point design is more than twice as strong as any split point drill design. Google, four faceted drills. I'm sure there will be loads of information with illustrations of what the four & six faceted points look like. Four faceted points can be ground by hand on any type of helical or spade type drill. I use these type points on carbide drills when drilling hardened & difficult to cut metals. They are used without the use of any coolants & when properly ground, they will cut without generating any heat. These things are not new, they have been used in tool rooms for many years!

Jim Allen

 

[Brad Christy]

Jim,

Those look like what I was referring to. I don't think I've ever heard them referred to as "faceted" drill points, but rather just "split" point. I've never had any luck doing this by hand. It's a skill I never HAD to acquire. I've always had a Black Diamond drill grinder at my disposal. Lucky, I guess.

For others,

While you can "split" any drill, The commercially available ones are usually made with a considerably thicker center web (thinnest cross section, measured through the flutes) for greater strength. If you grind a standard drill point on one of these drills, it won't cut worth a crap, because the web "bit" (non-cutting ridge at the tip, where the two ground surfaces meet) is too long and takes too much force to deform the material out to the cutting edges. The spit point brings the cutting edges all the way to the center, so there aren't any "non-cutting" edges, reducing cutting force considerably. Lesson's over......

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC

 

[Jim Allen]

Split point drills & faceted point drills are two very different things. Here is one site that will explain the difference; http://www.mmsonline.com/articles/choose-the-best-drill-point-geometry

JA

 

[Terry Keeley]

Thanks guys!

Jim & Brad, I appreciate your valued input, you guys have "been there, done that" your entire lives!

The selection of drills gets pretty slim (for ones & two's at least) when you're talking 1/16" & aircraft length. I was able to find Dormer taper & "extra" length (3 & 6") 130* cobalt with a "notched" split point. That corresponds to the "modified split point" in your article Jim, which they say is "especially outstanding for stainless, Inconel, titanium, and other difficult metals." I'm going to take a good look at them under a loup and try to duplicate the grind with my Black Diamond grinder. I've done regular split points before but not with the notch. Not sure how many holes I'll get before having to re-sharpen but I know Ti doesn't stand for dull tools. Just got my Royal MT5 to 5C adapter and Hardinge collet, hope to get the drill running to less than 1/2 thou.

Thanks for the Moly-D suggestion, did some tapping and that stuff is amazing! For the drilling & milling I'm going to run Rustlic coolant at a high concentration. The fixture to hold the blanks has a drill bushing to start the hole off straight, I'll go with a stub length drill, taper length and finish the last 1.5" with the long one. Hopefully with the right feed/speed and peck depth (G83 code) I'll get some straight holes. My goal is to end up straight to within 10 thou. in 4", that way the blades can be as thin as possible...

 

[Dan Kramer]

wow, it isnt just r/c racing anymore is it??lol

 

[Tom Foley]

Split point drills & faceted point drills are two very different things. Here is one site that will explain the difference; http://www.mmsonline.com/articles/choose-the-best-drill-point-geometry

JA

Great info here , thanks for sharing .

 

[Brad Christy]

Terry,

Your BlackDiamond is going to do the faceted point as Jim pointed out. Also, you can't go wrong with cobalt drills.

Something to consider..... If you're going to do the grinding yourself, and you've got the length to spare, snag off all but the last 1/2" of the drill flutes and regrind from there. This should help a lot in keeping the hole straight, but you'll have to make shallower pecks in your drill cycle. This goes for all three drill lengths you intend to use. The less flute length you have, the less the drill will wander. This will also reduce the chance of the drill twisting in the hole and breaking. The drill bushing should eliminate the need for "spotting" the hole for starting the drill straight. I've never had good results drilling a hole without spotting it first unless I was just opening up a hole that was going to be "trued up" with an end mill or boring bar or circle milled to finish. It's been my experience that drills will always walk around a bit before they dig in, even if they are called "self centering". This is why dowel holes are always "drill, mill, ream".

With a water soluble oil based coolant, you'd better keep a very close eye on things. You may want to start at nearly full concentration and thin it down a bit at a time until you start to see evidence of galling along the shank of the drill. I've had absolutely no luck at all with anything other than cutting oil. Tap-Magic is wonderful for shallow holes in Ti. With the depth you're looking at, I'd venture to guess you'll be using the Moly-Dee before you're done. Ti likes to weld itself to steel. Oil should prevent this, but I don't think the water will do much. I'm sure you'll keep us posted.

Jim,

Yup. Those are all pretty much "split point" drills in every shop I've ever been in. Not arguing with you, just been my exposure on the topic. I think what they are referring to as the "modified split point" is a standard drill with the web "split" at the point to eliminate the non-cutting bit at the center. I've done this and seen many others do this when conditions required it. The faceted point drills are the ones with the much thicker web to withstand the higher torsional forces involved, and they require the faceting to create a true "split" to eliminate the web at the tip.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC

 

[Ron Zaker Jr]

If/when you go full CNC, you may find programming/CAD/CAM displacing-replacing your boating hobby. Hmm I see an EDM power supply and stepper controller in your future.

You never know, wouldn't be that hard to add another axis down the road. My toolmaker buddy (another Rudy BTW) converted his lathe to full CNC a few years ago, even added a 3rd axis. He built this V8 from plans and is currently working on an inline 4 cylinder for his Chris Craft...

That's cool TK. I don't know if you ever heard of Connely engines,but his shop/home is right by my office. He took there it's cool man.

 

[Terry Keeley]

If/when you go full CNC, you may find programming/CAD/CAM displacing-replacing your boating hobby. Hmm I see an EDM power supply and stepper controller in your future.

You never know, wouldn't be that hard to add another axis down the road. My toolmaker buddy (another Rudy BTW) converted his lathe to full CNC a few years ago, even added a 3rd axis. He built this V8 from plans and is currently working on an inline 4 cylinder for his Chris Craft...

That's cool TK. I don't know if you ever heard of Connely engines,but his shop/home is right by my office. He took there it's cool man.

Sweet! That's a Connely V8 he built from plans, but completely from scratch!

I chromed and ground the cast iron liners (20 years ago), rings sealed much better...

 

[Terry Keeley]

Terry,

Your BlackDiamond is going to do the faceted point as Jim pointed out. Also, you can't go wrong with cobalt drills.

Something to consider..... If you're going to do the grinding yourself, and you've got the length to spare, snag off all but the last 1/2" of the drill flutes and regrind from there. This should help a lot in keeping the hole straight, but you'll have to make shallower pecks in your drill cycle. This goes for all three drill lengths you intend to use. The less flute length you have, the less the drill will wander. This will also reduce the chance of the drill twisting in the hole and breaking. The drill bushing should eliminate the need for "spotting" the hole for starting the drill straight. I've never had good results drilling a hole without spotting it first unless I was just opening up a hole that was going to be "trued up" with an end mill or boring bar or circle milled to finish. It's been my experience that drills will always walk around a bit before they dig in, even if they are called "self centering". This is why dowel holes are always "drill, mill, ream".

With a water soluble oil based coolant, you'd better keep a very close eye on things. You may want to start at nearly full concentration and thin it down a bit at a time until you start to see evidence of galling along the shank of the drill. I've had absolutely no luck at all with anything other than cutting oil. Tap-Magic is wonderful for shallow holes in Ti. With the depth you're looking at, I'd venture to guess you'll be using the Moly-Dee before you're done. Ti likes to weld itself to steel. Oil should prevent this, but I don't think the water will do much. I'm sure you'll keep us posted.

Jim,

Yup. Those are all pretty much "split point" drills in every shop I've ever been in. Not arguing with you, just been my exposure on the topic. I think what they are referring to as the "modified split point" is a standard drill with the web "split" at the point to eliminate the non-cutting bit at the center. I've done this and seen many others do this when conditions required it. The faceted point drills are the ones with the much thicker web to withstand the higher torsional forces involved, and they require the faceting to create a true "split" to eliminate the web at the tip.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC

Thanks for the suggestions but I won't be able to cut the drills back, the flutes run most of the length:

Been doing quite a bit of searching around on a professional machinist's forum (Practical Machinist) and that's what some guys were using for coolant. They seemed to think the cooling aspect was more important followed by lubricity, but most did run the concentration up from the usual 10% or so. They may just be limited to what their shop uses tho, not sure.

I made two rudders for my SAW boat a few years back and just used HSS drills and brushed on Tapmagic, worked pretty good but the chips came out blue and the hole wondered a bit. I used a full synthetic tapping fluid, "Super Tapzit" for milling and it seemed to work well, think that would be better?

http://synlube-mi.com/products/pure-synthetics/tapzit

What coolant do you use cutting your rods?

 

[Brad Christy]

Terry,

I use Blauser for coolant in my spray mister. Hangsterfers is a usable, less expensive alternative, but I find the Blauser stays in solution better. In a spray mister, the coolant sits in the tank and is not kept stirring like it is in a flood coolant system, and the Hangsterfers had a tendency to form globs of raw coolant that would eventually clog the supply line to the misting tip. Really, anything that is mineral oil based is going to work about the same way. I've been forced to use cheaper stuff when I worked for other shops. One shop switched from Blauser to Wallover, which is NOT mineral oil, because it was cheaper. What I found was that it was very sticky and was very difficult to keep from turning into what I thought resembled glue on/in the machines. If you let it dry, it was Hell getting it off, even if wiped immediately and still wet. With mineral oil coolants, all you do is just add some new coolant and it wiped right off. On the grinders, the Wallover would leave behind a film that harbored the grinding swarf and you had to firmly wipe the chuck clean with a rag to get it ready to place parts. With the Blauser, a squeegee and a quick wipe with a rag and you were good to go. I'm not sure what the base is in the Wallover, but it's not mineral oil.

Lubricity is a wonderful combatant to heat build up. Where you're going to have the greatest problem with a steel drill in a Ti part is not at the point of the cut, but the shank. I'm here to tell you, you are going to have heat at the point of cut, regardless. You'd almost be better off running water over the outside of the rudder blade and oil at the point of cut. Play around with it and see what you get. My experience tells me lubricity is king. Lubricate the cutting edge first, deal with the heat second. Heat is a product of friction and lubricity is the answer to friction. I think you'll find the Ti welds to the cutting edge too much to trade lubricity for cooling.

Look into "aircraft drills". They are long shank, relatively short flute drills, made specifically for reaching past "obstacles". I've seen them 12" long with only 2" of flute, even in sizes like what you're working with. I personally have a .080" drill that is 6" long with only 1/2" flutes that I use to drill the holes in my 7075 rudder blades.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC

 

[Brad Christy]

Terry,

I have four metalworking fluids in my shop. I use WD-40 for plastics, aluminum, copper and such, TapMagic for steels, stainless, Ti and other exotics, Moly-Dee for tapping stainless or larger taps in steels and even aluminum. And then I've got some of what the sales rep referred to as "Tapping Honey." This stuff is NASTY. It pours just about like honey, is nearly impossible to wipe off and gets on EVERYTHING, but it works in the most extreme tapping conditions I've come across. It is unfortunately no longer available. The sales rep told me it has chlorinated paraffin in it, which our EPA, in all their infinite wisdom, classified as a CFC, so it had to be pulled from the market. The supply company had a 55 gallon drum of it they couldn't sell, so they give it out to customers with exceptionally difficult tapping situations.

To elaborate on my selection of cutting oils...... I use my spray mister for all milling operations for the "chip evacuation" aspect. There's nothing worse on cutting tools than re-cutting chips. For drilling, I use oils as described above. WD-40 for softer materials, TapMagic for the middle-ground materials like steels and most stainless, and Moly-Dee for Ti, Inconel and other nasty crap. For tapping, it's a bit different, because I use form taps for every application I can, and they require for torque than cutting taps, and oil selection varies depending on size and type of tap I'm using. It's just something learned over years of making mistakes.

For what it's worth, and a bit off-topic, I suggest using form taps as I do. They don't make a chip, so you can drive them right into the bottom of a hole without having to clear the chips out as you go. They are much sturdier than cutting taps, because they don't have the cutting flutes in them, so they don't break nearly as often. They produce a stronger thread than cutting taps, because they don't interrupt the grain structure of the material. Things to keep in mind: You must drill a considerably larger hole in preparation for a form tap than for that of a cutting tap. Charts are available. I have never tried a form tap in Ti because of the welding tendency (others may chime in here if they've had success). I have tried a form tap in 440c stainless and it didn't work out well. Let's just say form taps are much more difficult to extract than cutting taps and Heli-Coils are a toolmakers best friend. I would guess that this applies for all 400 series stainless material. And lastly, form taps work extremely well in Delrin, nylon and such. The screw goes in very tight, but it does, indeed, go. Think of it as a Ny-Lock nut kind of thing, and the screws won't vibrate out nearly as easily.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC

 

[Terry Keeley]

I'm gonna try the "Rustlick Pro CF" and bump the mix up to 25% from the usual 3-10%. I'll keep an eye on the chips to know how the drill is doing and inspect &/or sharpen after each part as necessary. I'm lucky, I have time and don't havta been making these for profit!

Came across some info on some "old school" cutting oils that worked like a charm but had some nasty chemicals in them and are now banned, prolly similar to your "honey". That Moly-D is pretty amazing stuff for taping tho, better that any TapMagic I ever used.

I used HSS aircraft drills to so the two original blades I made but couldn't find any in cobalt. Not sure if the shank is tapered on them but these parabolic flute drills taper down so as not to rub in the hole, important for Ti.

Haven't used any form taps but may give it a go down the road. For this job I got some Widia (formerly Greenfield) taps the guys on PM recommended for Ti. I havta tap a couple of 4-40 holes as one of the last ops and am always nervous about the tap grabbing. The Moly-D will help I'm sure...

 

[Brad Christy]

Terry,

I use the TapMagic whenever I can get away with it, and it works as well as anything else I've found. I only use the Moly-Dee when I absolutely have to. Like I said: It stinks. It also has a tendency to get on everything and doesn't like to wipe off easily.

The taper you mention may work against you in allowing the drill to wander off. Look into Guhring for the drills. I'm sure they have the drills I'm referring to in cobalt. Keep them in mind if you have problems. Those long flutes may also become a problem. When the tip cuts into the material, the flutes are going to twist. When they do, the diameter swells. Just one more thing for you to worry about..........

I've always gotten the best results from OSG taps. I had one job with fairly deep M10x1.5 threads in A-2. I bought a couple YMW taps because they were the most readily available at the moment. They started breaking down in the first part, with ten to do. I picked up a single OSG tap and finished the job with it. Widia seems to be a good product in nearly everything else I've used from them, and we've all known Greenfield forever, so I have no doubt their taps will work well.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC

 

[Terry Keeley]

Got it up to speed:

 

[Terry Keeley]

Starting on the blanks:

 

[Terry Keeley]