325 Tooling Experience

[Mike RZMachine]

I just hauled my journeyman 325 back last week, and as i get the wiring in place for the RPC, i'm looking at tooling.

i really don't know what to look for in terms of tool offset, other than shorter would be more rigid/less overhung load on the spindle. should i look for toolholders with the same offset to avoid cranking the knee up and down all the time? if that is the case, would the drill chuck be the length to work around? should i just buy a few er collet chucks to start with and put drills/mills/taps into them and avoid a drill chuck to start with?

thanks,
Mike

[MechWerks]

I am going through the same basic process. The main thing is what will you be cutting with the mill? It seems keeping a short or fairly equal gage length to keep the tools within the Z range would be the way to go..and keep short for rigidity. There are so many different tools (boring heads, chucks, tapping heads, end mill holders, ER, TG, etc.). The controller manual indicates a reference tool longer than the cutting tools is used to zero the Z axis, then the other tools are touched off and referenced in the tool catalog. Still pretty much limits you to the 6" quill and the table only allows more room between that quill range and larger depth work.
You can spend a few grand on an array of tools...or do your homework and tool to your needs. Still seems most people start out with some basic end mill holders over a range of sizes. A couple ER holders and collet sets, a drill chuck...and keep drooling over the tool catalogs.

[Michael M]

Mike, you'll often get one tool in a job that requires you to reposition the knee.

For example, my SPD-7 Tapmatic tapping head in an EM holder with a 1/2-13 spiral point tap is 12" long under the flange while an ER16 collet chuck with a 1/4" spotting drill in it is 3". The tapping head also needs 1.5-2" clearance above the work to have the tap be safely out of the hole before going to the next position (and yes, I found that out the exciting way).

So how do you deal with both a 3" and a 14-15" (effective) tool when you've got 6" of quill movement? The only thing I've been able to figure out is saving the long tool for last and then resetting the knee and part zero for it.

I will recommend you get a set of screw machine drills. You should use them because they are stiffer than the longer jobber drills, but also because they usefully shorten up a drill chuck/drill combo.

Drill chucks are handy as you don't have to rummage around for the correct collet but the length issue can be annoying at times. A screw machine drill in an ER chuck is going to be about the same length as many mid-size (1/2") EMs. There are also ER chucks that have internal nuts that recess the tool into the body of the tapered shank and I'm going to be looking at some of those. You may end up with a deep hole that will force you to use a jobber drill as a screw machine drill will be too short. ER chucks are likely to run truer than a drill chuck.

I think that you might be OK going with just ER chucks to start. You'll need at least one full set of collets for whichever series you get to cover a full range of sizes. You may also need a couple different series of ER chucks. ER16 looks to be .020-.433, ER32 .080 to .787" and ER40 .12 to 1.02". The ER16 nut is significantly smaller than the ER32 if you need to get into a tight space.

I've got a couple of ER16s and the rest ER32s. I have a full set of collets for each series and I bought extras of the standard fractional sizes as I may be using several different EMs that all need the same collet (1/2 rougher, 1/2 finisher, 1/2 ball nose).

The collet chucks are more versatile than the drill chucks as you can mill or drill with them.

I haven't had much call for EM holders. I use them for things like the reference tool or to hold the probe. I bought a CAT40 shell end mill shank for my face mill. Shorter/sturdier seems like the way to go, and EM holders often don't fit that.

You might want to look into the ER chucks that Frank Mari at Maritool.com offers. They are very reasonably priced and the "pros" at PM have had nothing but good things to say about them and Frank's service. Frank is supposed to be working on the internal nut collet chucks and when they come available (he said they'll be about 10-15% more expensive) I'm going to get some of them.

I hope that is of some use to you. I am NOT a "pro" so don't take the above as an expert opinion.

cheers,
Michael

[Mike RZMachine]

i've read lots of good things about mari tool. that plus very reasonable prices will make me go there for the first round of tooling up. i was also thinking about er25 collets, as i have a few for my emco mill, but it looks like er 16 is the way to go for the sake of tool clearance.

the other thing i'm wondering about is if i can tap using a floating tap holder, or do i need a full out reversing tapping head? i know my machine doesn't have the required feedback for rigid tappng, but i don't know how to check if it has the capability for normal tapping. the delta 20 manual has the cycle listed, but the tree manual doesn't say anything about the machine being capable. i have the 6000 rpm spindle, if that makes any difference.

i actually came across a machinist who's making some parts for my work who started out with a tree 325, and he agreed with the collet chucks for most work, especially to start out.

has anyone put a servo drive on their knee to run quickly between reference heights? is the leadscrew under there reasonably accurate, or at least repeatable? or will i need a direct read encoder/glass scale to reference height? i thought it would be a slick addition to have a motion control that could move to a few preset heights (or height deltas) which would correspond to different tools. this would allow me to move the knee when i pause the program to change tools. i guess the first step would be a used servo/gearhead to drive the knee electrically, then set up a motion control to servo to position, always approaching from the up direction.

i should probably focus on getting the machine installed and running first.

Thanks,
Mike

[Michael M]

I went with the SPD7 because it self-reverses and it made sense to me to not be starting/stopping/reversing/stopping/starting etc the spindle. I don't know if the tapping head might also be a little more forgiving compared to a floating tap holder in case you get the feed/RPM just a little too far off. I do verify the spindle RPM with an optical tach when doing the tapping as I haven't gotten the spindle drive and control perfectly dialed in so that commanded RPM is always actual spindle RPM. It isn't dead linear throughout the 6000 RPM range and I think that there is probably a drive setting that needs minor tweaking. Figuring out which one is the issue.

A good thing about the 325 is there is a lot of knee movement available, though with the long tapping head/tap setup I've needed every bit of it. The bad thing is that it takes a LOT of cranking to use that knee movement.

I'm going to see if a 1/2" drill will have enough oomph to crank the knee. But I'll have to make an adapter as the shaft on the knee is too big for the chucks on either of my 1/2" drills. I've seen people talk about doing this on a Bridgeport, but the knee//saddle/table assy on a Bridgeport is probably not near as heavy as the Tree. Tree did offer a powered knee but AFAIK that was not under control, it was just an axis drive like you'd find on a manual machine (though with a much bigger motor).

If I've needed to reposition the knee I've always reset part zero in Z. Having a DRO on the knee would be very convenient, but I'm not sure I want to put money into that as most of the parts I do (if tapping is avoided) mostly fit into the available quill movement, presuming I've organized the tool holder/tool lengths to minimize the overall variation in them.

cheers,
Michael

[MechWerks]

www.surpluscenter.com often has some gear motors of various sizes/types that are usually a pretty reasonable price. Something could be rigged up to reduce the crank work on the knee. You could play around the CNC control of the knee or even install an encoder to read the knee screw (but height accuracy would most likely not carry a high degree of accuracy). Seems most times that a tool touch off and zero would make a knee move relative to the program (talking out my butt here...not much experience). There are some long throw digital scales available (import) that can just be bolted in place with little work and have a digital read in absolute and incremental settings...fairly low cost and higher end stuff is available to suit your $$. Some of the scales even have outputs and can be attached to remote readouts...or Newall, etc. have single read out scales at higher $$. If you controller has a 4th axis it could be that an encoder scale could be added just a read out.

Sorry, I look at these things as challenges. There are all kinds of electonic kits and parts available today to make up all sorts of gagets if a person is inclinded. I rigged up a timing belt (driving a hall effect switch) to a stepper driver ($12 kit) that turns a rotary table so spirals can be cut on a manual mill...sort of an electronic driven universal dividing head. If an encoder were used instead of the timing belt then the spiral could be changed at division or software divisions of the encoder.

I will put a second on Mari Tool...low cost, fast ship, keep in touch throughout the order and ship process, high quality tool holders.