Screeching halt to milling mold blocks

[44man]

My blocks need to be reduced in heighth yet. I set the mill to hog a little and the darn end mill kept cutting deeper and deeper. The R8 collet just doesn't hold the cutter no matter how tight I make it. It pulls down into the aluminum.
I had to order a set of R8 arbors from Enco. So all work is done for a while until they arrive. I didn't want to put a fly cutter in a collet either.
I bought the Granite used and it didn't have the arbors.
I also have a complete set of 5C collets but nothing to use them in.

[leftiye]

Arbors (holders) should help, but in a heavy cut, the endmill might still try to dig in. Try to get endmills with the flat to lock in the holder.

Is your aluminium pretty soft? I haven't had my endmills dig in. You might look at endmills with less dead angle (straight flute maybe). Cheaper than arbors maybe. Or an indexable carbide surfacing mill (not cheaper, look on eBay, or for sales).

[rusty marlin]

I run my bridgy almost every day.
Are you sure you don't have a metric tool in an inch collet? or vs versa?

I take some wicked roughing cuts like .025 x 1.5" in steel with good carbide roughers and have never had the tool pull out. It wants to, I can tell by the sticky quill when I unlock it and by how hard I have to smack the drawbar to get the collet to release.

[Bret4207]

Get all the lube off the tool and the collet. Had a similar thing happen in my teeny, tiny Atlas. Ended up dusting a bit of powdered rosin on the tool shaft and it helped a lot.

[R.M.]

Take a magic-marker and paint the shank with it. It'll add a bit of friction to it and grip a bit better, but yes, it sounds like the shank isn't the same size as the collet.

[deltaenterprizes]

Mic the drill rod it may be undersized a thousandth ,also try another collet,you should feel drag when the tool goes into the collet.

[44man]

It's a 3/4" collet and a 3/4" end mill. Works OK to .050" but I need to remove more. The aluminum is hard aircraft stuff. I had the same trouble when side milling with it.
I read that a lot of guys have the same problem with collets and light cuts are needed.
I can't see the collet holding my fly cutters either.
I got a whole set of arbors from 3/16" to 1-1/4" for $78. Marked down from $96.
Nothing better then locking a setscrew in a flat.

[xr650]

You might check your draw bar also. The hex head can start pulling off the rod over time. Allowing the tool to loosen some.

[floodgate]

44man:

Check your Granite parts catalog; I think they make a face-mounted holder/collet-closer that will take the 5C collets. I had one made up for my Smithy AT-300 (an earlier form of the 12-20), but they later came out with one just like it, that bolts onto the mainshaft flange in place of the chucks, faceplates, etc. The 5C collets are cheap enough (import type) and useful enough to make them well worth the cost of the holder/closer.

Floodgate

[Willbird]

The only problem with the endmill holders is that the tool ends up hanging out a whole lot more.

Bill

[grumpy one]

I get the endmill dig-in problem, using ISO-30 toolholders and a set-screw to hold the cutter in the toolholder, because I use a flat on the endmills, not a proper indentation. The reason I don't use a proper indentation is that it's a bit difficult to make them, considering how hard the shank of the endmill is.

I don't believe your problem can be overcome by squeezing the collet tighter - more likely you'll destroy the thread in the collet. While an adhesive will probably work, it is likely to corrode the interior of your collets over time. I have two ways to avoid the problem: use a fixed toolholder (carbide tips bolted directly to the toolholder), or use a screw-in endmill in a Clarkson-type self-locking collet toolholder. The screw-in endmills are considerably nicer to use than the plain ones, but may cost more. I tend to buy second-hand endmills and crudely hand-sharpen them for everyday work, but when it counts I dig out the Clarkson rig.

FWIW, my view of R8 toolholders is extremely negative, but not because of their grip on the tool. The problem is that they attempt to transfer torque from the quill through a combination of a taper that is far too small in diameter, and a pretend-key that is actually just the tip of a cap screw. Real milling machines use ISO toolholders: 30, 40 or 50 series depending on the size of the machine. 30 series toolholders, in particular, are cheap and plentiful second-hand because they have been the standard toolholder for multi-function CNC machining centres for at least a decade.

[44man]

I have to check on the 5C holder. I am retired on a fixed income so stuff gets bought slowly. I still need a 4 jaw chuck and a face plate.
I haven't had any luck selling the smaller Smithy CB 1220 yet. I was hoping to buy what I need with the money.
I don't like the R8 thing either but getting such a good deal was hard to pass up.

[windrider919]

I too had a problem of the work 'sucking ' the tool out of the R8 holder. Some of us cannot afford a "real" mill and so have to do the best we can with a foreign Drill Mill. But with a few modifications it will work just fine.

First of all, I disassembled my quill shaft and drilled out and re-threaded the small hole where the cap screw 'key for the R8 is. I put in a larger dia. grade 8 setscrew that had the tip machined into a key. Mill a shallow!! counter bore flat in the quill shaft around the key screw hole to give a contact surface for the jam nut to lock to. Remove just enough to break the radius of the shaft OD. Secure the setscrew with a jam nut in the vertical position. This gives me about twice the holding material as the old screw. I have never had this strip ever again!!!!!!!

Next, I bought a second set of cheap R8 [Chinese] and drilled and tapped a 1/4-28 NF set screw hole in the body at the top of the taper. Use a die grinder to radius the inside of the new hole because you need to remove the ridge of displaced metal that would make the holder 'tight'. If the tool I am using does not have a flat then I grid [a small] one. The only drawback is you must remove the collet to change the tool but I only use it when I think I will have a problem. Otherwise I just use an unmodified R8.

The other mod you should consider is buying a cheap digital caliper and modifying it to replace the cheesy quill height indicator. Several sites on the net show how with pictures

[44man]

My outfit came with a DRO. It holds steady as the end mill cuts deeper and deeper so I know the thing is creeping out of the collet.
I did what you guys suggested and managed to finish my blocks before the arbors got here so all is well again.

[badgeredd]

My outfit came with a DRO. It holds steady as the end mill cuts deeper and deeper so I know the thing is creeping out of the collet.
I did what you guys suggested and managed to finish my blocks before the arbors got here so all is well again.

Here,s an old toolmaker trick, this old tool maker learned from an old tool maker 30 or so years ago. Buy some Dyken either the spray can (easier & more precise) or with the brush can (Cheaper) and paint the surface of your end mill with it. Like the marker is adds a little friction hold on the OD but it seems to be a bit stickier to hold the endmill. Also make sure your draw bar isn't contacting the end mill in the collet. Although aluminum machines quite easily, it helps to add a little coolant to the milling operation to let the chips freely release. I often just dribble a little cutting fluid on the surface I am cutting. Cutter speed can also add to the problem. Too fast will heat the chips & work piece and cause the cips to want to stick, thus dulling the cutting edges and making the cutter pull down. Another possible cause is tring to move too quickly across your work piece which adds chip load and enhances the tendancy for the cutter to pull. It is all about experience and you'll get there with time and experience.:-D:-D

[44man]

Super ideas! :drinks: You guys are great, thank you.

[deltaenterprizes]

WD-40 works well as a cutting fluid on aluminum.

[44man]

It sure is, I use it when cutting with the cherry. I will have to use it on the blocks too.

[Buckshot]

...............You've solved your problem so my response is just something else to read. As Grumpy one mentioned, the R8's are kind of light compared to the NMTB 30 or 40 series or the Cat V flange. However, unless they're sprung or have been damaged the R8's will hold very well, assuming they and the tool shank are clean and free of oil and/or chips. As with any slit collet if chips or debris gets into the slits, it can keep the collet from holding as well as it should. Naturally the drawbar HAS to be tight.

If your drawbar doesn't have a bearing flange, it would be a good idea to make one and put it on the drawbar. This way it has a nice broad flat (and lubed) surface to bear against.

With the above in mind, simply looking at the thinness of the R8 in sizes over 3/4", I bought 3 R8 shanked EM holders of 3/4, 7/8, and 1" ID's. Also mentioned, to use them the shank of the tool has to have the Weldon cut for the sockethead screw to rest in. A possible problem with cheap endmill holders can be that when the tool hole is bored and honed the shanks' offset isn't taken into consideration. The hole HAS to have clearance and the setscrew will offset the shank to the clearance allowed. As a consequence the tool won't cut evenly on all flutes. Good EM holders are bored and honed with the hole offset toward the screw to eliminate the problem.

I don't know how much you have to remove but a flycutter would be a good idea. In aluminum especially you'd want a lot of rake and bunches of clearance. Offset the flycutter to get the longest chip possible in the tool's sweep across the material. You'd need to have the flycutter set well off the centerline of the blocks. The tool would take a very small bite (naturally depending upon feed) as it enters the material and the width of the chip would increase as the tool sweeps across.

.................Buckshot

[44man]

Buckshot, could you post a picture or a drawing of the fly cutter bit for me?

[Flinchrock]

My blocks need to be reduced in heighth yet. I set the mill to hog a little and the darn end mill kept cutting deeper and deeper. The R8 collet just doesn't hold the cutter no matter how tight I make it. It pulls down into the aluminum.
I had to order a set of R8 arbors from Enco. So all work is done for a while until they arrive. I didn't want to put a fly cutter in a collet either.
I bought the Granite used and it didn't have the arbors.
I also have a complete set of 5C collets but nothing to use them in.

Something else that works, is to take some 400 grit oil based lapping compound
on your cutter where it rides in your collet, hold the collet fingers with your hand applying pressure and lightly lap the collet with the cutter. All you are going to do
is "surface" the Collet, not try to remove a lot of metal. Clean everything up and you will be ready to hog!

[44man]

Another great idea! I have done that with scope rings but never gave it a thought for the collets.

[Buckshot]

Buckshot, could you post a picture or a drawing of the fly cutter bit for me?

............Sorry, no picture. You want the tip of the tool to 'just' catch the far edge of the blocks in the vise and then sweep across in the longest arc possible. Due to the feed, as the tool sweeps across it takes an increasingly wider cut. Feed needs to be set so as to not exceed the width of the tool's tip. If not, then you'll leave a ridge of material behind. Done correctly you'll have an exceedingly smooth clean surface.

............Buckshot

[44man]

OK, I will try it on scrap to see what my slowest feed will do.
I still need to drill all of the pin holes and saw the blocks in half. The band saw went dull again so I need to grind 720 teeth---GROAN! :???:

[deltaenterprizes]

What do you use and where do you get your pins?

[44man]

I buy drill rod from Enco for the pins.

[grumpy one]

The band saw went dull again so I need to grind 720 teeth---GROAN! :???:

This probably doesn't come as a surprise, but if your band saw gets blunt in any period less than multiple hours of use, you are doing something wrong: using a carbon steel band, which is insane for cutting metal; forcing a tight-radius cut and losing the set; or you are overheating it.

Just to make you feel badly, I use ordinary HSS hacksaw blades in a filing maching used as a jigsaw instead using of a bandsaw (I refuse either to weld bands or buy them) and each hacksaw blade lasts many, many hours. I don't resharpen them - hacksaw blades are pretty cheap at fleamarkets.

[44man]

I use a Simonds blade a friend sent me. It is just for aluminum and cuts 2" pieces like butter, as fast as cutting wood the same thickness.
However, I cut all of these blocks and it has slowed down.

[Buckshot]

..............Something has GOTTA be wrong someplace! Maybe 2-3 years ago I bought one of those Harbor Freight 4"x6" horizontal bandsaws for something like $149 on sale. I think it takes 54" x 1/2" blades. When I bought it I also bought a half dozen blades with it, for like $6 to $8 each, various TPI. I'm positive at that price they had to be cheap common high carbon ones.

I have been totally blown away by this thing. I am using only the second blade! I've cut 6061, 7075, and unidentified aluminum, copper, 4140, 1045, common merchant stock low carbon, rebar, pipe, angle, and other junk. The motor will get so hot you can't lay your hand on it, but it has yet to stop.

I have looked at other blades, name brand blades with fancy stuff but if these $6 blades which seem to last forever do so well, why go for $18 blades?

............Buckshot

[44man]

Those metal cutting saws work because they run real slow and coolant is constantly fed to the blade. Tha bar also puts a constant pressure on what you are cutting.
I am using a bandsaw and the blade is onlly 80" so it goes around fast. No way to lube either without messing up the rubber tires.

[deltaenterprizes]

Try parafin for lube,just cut into a candle once in a while.

[Nueces]

Those metal cutting saws work because they run real slow and coolant is constantly fed to the blade. Tha bar also puts a constant pressure on what you are cutting.
I am using a bandsaw and the blade is onlly 80" so it goes around fast. No way to lube either without messing up the rubber tires.

If the blade goes around fast on rubber tires, my thinking is you're using a wood saw, with speed much too high for any metal, even aluminum. Wood saw blade speed is typically 3000 feet per minute, whereas aluminum needs about one tenth that and steel about one third less still.

If that is what you're using, that high speed is tearing up your teeth. If you have no other option, you could try the wax stick blade lubes and install a small rotating brush that cleans the teeth. Even with great care in feeding, though, you're at risk for regularly destroying your blade.

That sort of small horizontal/vertical bandsaw Buckshot mentions features slow, for-metal speeds and can be used in the vertical mode for hand feeding. Mine is a Jet. There is an active Yahoo group for these saws with lots of good poop on mods and setups.

Mark

[44man]

I do wax the blade but have no choice but to use the wood saw right now. Money, ya know. However I am almost out of scrap aluminum and if I have to buy it in the future, I will only need to mill it other then a short cut on the saw. I could do that by hand with a hacksaw.

[Boomer Mikey]

This set of fly cutters is inexpensive:
http://littlemachineshop.com/products/product_view.php?ProductID=1231

http://littlemachineshop.com/Products/Images/480/480.1231.jpg

This is a good, sturdy fly cutter with integral R8 shank that'll stay put during heavy cuts.:
http://www.lathemaster.com/images/FLY_CUTTER_-_R8.JPG

http://www.lathemaster.com/FLY%20CUTTER.htm

If you use carbide cutting tools use the brazed tip style... index-able lathe bits will break in interrupted cuts. HSS tools can be ground razor sharp resulting in beautiful results in aluminum.

A good video showing them in operation: http://www.youtube.com/watch?v=koYGLVGkRsI

Fly cutters can be dangerous... use these tools carefully, it's easy to see that loose cutting tools can fly and unsecured materials can cause serious issues.

Boomer :Fire:

[windrider919]

The fly cutter shown by Boomer Miley is exactly why I had to beef up the key on the quill shaft for the R8 collet. R8s WILL slip even if the draw bar is so tight the threads are about to tear off. The taper is just not suitable for heavy milling like taken for granted on other styles of collets / milling machines. That is why it is only used on lightweight machines. The cone is too short and hence the angle is wrong for power holding too.

The first time I sheared the index key was when using a fly cutter. The shocks from the cutter hitting the work were too much for the taper which slipped and the key was taking the load and sheared.

However, that being said, see my previous post about upgrading the key. Every brand of machine that uses R8s has aprox the same sized index key to keep the collet from turning as tightened. The key was not really meant to keep the collet from rotating under load but if you modify like I say you will be able to use a 3.5" fly cutter making a 0.070 or 0.080 cut in a 3" aluminum block. The difference between the stock key screw with a tip of 1/8 X 1/8 and the improved key of 1/8 X 1/4 is obvious. It just gives the taper that little bit of extra holding power somehow. And if you add in the tool holding setscrew you can 'fly' at amazing metal removal rates. Of course I had to build shields around my mill to stop the hot metal chips and coolant from flying 20 feet!

[theperfessor]

I've found that investing a few dollars in some serrated edge roughing end mills of various diameters can save a lot of time and grief when making deep cuts without cutter slippage. I use them on steel and aluminum. The design reduces the spindle load compared to a regular end mill. The thread-like chips seem to flush away easier and cause less trouble on recuts. And I've never had any of them slip in a clean R8 collet.

Try 'em, you'll like 'em.

[Boomer Mikey]

44man's Smithy 1324 is a light duty machine... (I own one) I consider 1/2" end mills max for the machine and light cuts of 0.025" heavy for the machine too. The machine isn't very rigid and the power goes through 2 sets of right angle gears for milling operations. There's more going on than collet slipage... the millhead gets to jumping around pretty good.

I actually took the millhead off my machine; it's better than no mill at all though. IIRC the Smithy 1324 R8 Mill Head doesn't have an index pin.

Roughing mills really reduce the power required and vibration during heavy cuts but nothing can beat a fly-cut finish pass with a sharp tool in a rigid setup for quality of finish.

This is a 1500 rpm, 0.100", 10 IPM pass made with a 2" Lovejoy 5 insert face mill specifically made for low power machines but still required 1.5 HP @ 220V for this cut in my Industrial Hobbies benchtop mill.
http://www.cnczone.com/gallery/data/9017/Dovetail_Spindle_Mount0005_4_1_1.JPG

The square carbide inserts are razor sharp and the face mill is well worth its $200 plus price tag with a set of inserts.

http://www.cnczone.com/gallery/data/9015/Industrial_Hobbies_Mill.JPG

The face mill and fly-cutter are in the rack with other tooling.



Boomer :Fire:

[44man]

Very nice stuff there.
My 1324 does have a locating pin and it is easy to change but must be done from outside through a hole.
My flycutters will only be used for light cuts on the inner block surfaces so that will be no problem. I just need to radius my cutter a little more. I also use it to cut the vent lines.
Now the stupid question! [smilie=1:
I have dial up and had to go to my friends to watch the You tube video's. Is there any way to save them to a DVD?
There is a wealth of information that I can't watch. I used to just let the video load by minimizing the site, then I could re-play in normal speed. It won't do that anymore and starts all over again with the little loads and jumps.

[Boomer Mikey]

Very nice stuff there.
My 1324 does have a locating pin and it is easy to change but must be done from outside through a hole.
My flycutters will only be used for light cuts on the inner block surfaces so that will be no problem. I just need to radius my cutter a little more. I also use it to cut the vent lines.

Sorry, I don't know how to save the videos. Go to the Tormach website for more show and tell... http://www.tormach.com/mfg_database.htm

I finally got my PCNC-1100 inside the shop a few weeks ago and I plan to use a fly cutter with it to make all those vent lines in blocks with a "G" code program.

Have fun 44man,

Boomer :Fire:

[44man]

Thank you.
I am out of business though. I was milling handle slots with a 3/16" end mill, just taking light cuts and the Granite stopped. It will not start again. I have to call Smithy tomorrow.

[xr650]

I've found that investing a few dollars in some serrated edge roughing end mills of various diameters can save a lot of time and grief when making deep cuts without cutter slippage. I use them on steel and aluminum. The design reduces the spindle load compared to a regular end mill. The thread-like chips seem to flush away easier and cause less trouble on recuts. And I've never had any of them slip in a clean R8 collet.

Try 'em, you'll like 'em.

Try a high helix EM on your aluminum some day. They will out perform a rougher by a fair bit and acheive a finished surface at the same time. Kick the RPM up where it should be and you will not have chips on your part to worry about. Not much good for steel though. :drinks:

[xr650]

44man,
Sorry to hear your machine layed down on you.

Do you folks use coolant while machining?

[Boomer Mikey]

Thank you.
I am out of business though. I was milling handle slots with a 3/16" end mill, just taking light cuts and the Granite stopped. It will not start again. I have to call Smithy tomorrow.

I'll bet one of your motor brush wires unsoldered itself from the brush holder.

It has happened to me five or six times... it's a TEFC motor without a fan attached.

Attach a fan blade to the short end of the motor or get a fan blowiing on the motor during extended periods of use.

Boomer :Fire:

[44man]

Boomer, that's what happened. I soldered it back on and then called Smithy. They are sending me new brush holders because the wire is supposed to be silver soldered on.
My motor does have a fan but it didn't help.

[Boomer Mikey]

Boomer, that's what happened. I soldered it back on and then called Smithy. They are sending me new brush holders because the wire is supposed to be silver soldered on.
My motor does have a fan but it didn't help.

They sent me some new brushes but no new brush holders. I'm going to upgrade to the larger new motor around Christmas time when the price drops on them.

Boomer :Fire: