[sgt panties]

I bought the RF45 mill about two years ago from Wholesale Tool.

I'm largely self-taught as far as machining goes and I never had the advantage of working in a machine shop, so I can't tell you how good this mill is because I have nothing to compare it to. My machine has probably clocked a total of about 24 hours now, drilling or milling. This is my first serious machine tool.

I've dreamed about CNCing this and have done quite a bit of research along those lines, but would rather get some more experience under my belt. Automating the Z seems like it would be a bear.

I've had none of the leaks or bearing problems some people have reported. I just use plain non-detergent oil in the gearbox.

I've realized of late this mill is always marketed as a "mill/drill", not so much a "milling machine". The subtext I suspect is: "Sure you can mill with this machine in some cases, but if you can't you can at least use it for drilling."

Let me tell you why I am of that suspicion. I find steel much cheaper and easier to weld than aluminum so I fab a lot of my creations from steel.

If I clamp some 1/4 inch mild steel plate to the table and try to edge mill off 1/10 inch with a roughing end mill, and put my hand on the table, I feel almost no vibration. Good. But, if I put my hand on the head there is definitely vibration. Now is the head oscillating 1/32" in either direction? No. But I definitely feel vibration.

Now that I think of it I should have applied the same test to the column. I will follow up on that.

The quality of the cuts is good starting out, but of course I'm using a roughing end mill and the result is --well, rough. I don't use a finishing end mill, but rather clean the edges with a big heavy HF disk sander (which has served me remarkably well for a long time despite what people think of the brand.) Later, I think because of that vibration, the bit dulls and I get reduced travel and a "smeared" looking edge. It just seems to me the bit should last longer.

(I do a lot of edge milling to correct my horrible by-hand plasma cutter cuts. Even with a fence, I have a fairly nervous hand and the results are almost always crappy. In the few cases I have a beautiful cut, its out of square. But I digress.)

Vibration of course equals movement which is evidence of a lack of stiffness. Mind you I know enough to lock the Z and Y jibs and lock the spindle.

I'm running at 210 rpm and my roughing end mill is typically 1" in diameter. It's in a 3/4" R8 collet. Also I'm not climb milling. I mill in the (conventional) direction, whatever that is called.

The cut I described is reasonable, isn't it?

My rate of travel? Well I haven't measured it but I can tell you I don't try to force it. I'm probably putting about 5 ft/lbs of torsion on the X crank. At least 8 ipm but no more than 15 ipm.

Lastly I'm squirting some Tapmatic "Natural" cutting fluid on my cuts when I think it needs it.

Also know that I've learned (in addition to knocking off any dross) to grind off the skin of flat blueish steel that the plasma cutter leaves on the edge of the plate, BEFORE I give the plate to the mill. It seems the plasma leaves a 100th of really hard stuff that is hard on my bits.

Has anyone with a RF45 out there had this same vibration problem? Or is this machine just not up to the task of milling steel? Would a Bridgeport vibrate like this?

Any comments appreciated, even months from now.

[LUCKY13]

Any mill will vibrate when cutting steel. Just listen even to some of the very nice CNC VMC when they are cutting steel.


Now what the machine does with that vibration is important. I would beat that doing some work on your mill would help the surface finsih. Its just natural for these machines to need work on the gibs. The gib is part of your contact between mounts and table/column, ect. Plus it controls the slack between these parts.

These mills are quite capable, but there still not no bridgeport either. That said you can still do some nice work with them and the more you do to the machine the better it gets. A Bridgeport still vibrates, it just has more meat to control it.


CNC just helps so much simple by being motorized. The steady constant feed give better cuts, plus you tend to have more time to allow it to make these cuts which results in the ability to take lighter cuts and get even better finishes. A axis power feed can do the same.


Vibration will help dull a end mill cutter. But chances are the type cutters you are using are more the problem than anything. Plus you cant expect a end mill cutting steel to last but so long no matter how good it is. BUt buying better quality end mills with the right geometery for the job will always help a ton. And better quality cutters to begin with will help a lot to.


A good quality end mill for the job you would expect to pay anywhere from 20 to 100 dallors each. I am guessing you are paying this for sets, not each.


WIthout coolant ( which will help alot also) using cutters with a coating can help.


Now back to the machine. The gibs I beat are not straight. This makes it to where you can not take all the slack between the moving parts out. Using the axis locks will bend them also. Taking the giibs and working them flat will have a big effect on the machine ( sand them, scrape them). Also working on the screw backlash helps. Most mills have screw nuts that can be ajusted to take out most of the backlash.


Feed and speeds. You may find that going faster on your cuts might help. Ofcourse you have to listen to the machine but if the cutter is moving to slow it rubs the steel which causes heat and kills cutters.

Everything works together ot make things happen. Using a brush to apply your cutting fluid so you can keep it wetter would be good also. You dont want the cutter getting hot any.

So work your gibs out flat to get tighter slides/ways ( the machine will work so much better to).
Tighten your screws nut ajustments.
Get better end mills.
Use coolant/oil more.
Experiment with feeds,speeds and DOC when you get better cutters.
Also tramming the head in straight if your not doing this.


You will have vibration no matter what. But you can have less, and control it better.


BTW I think the seal and bearing problems come from machines that set a long time after taking the salty boat ride. When I got mine the upper bearings that where not covered in oil where rusty. Plus you need to clean out the head to remove any sand left there from castings (oil changes help this). Sand/glass is just rough on parts.


Jess

[arizonavideo]

A 1" cutter is a bit large for steel if you want the best surface finish, the larger the cutter the greater the cutting force. Standard HHS will dull fairly fast without water cooling. I would guess that the 1" cutter is fairly long too which will shake more.

I would get a 1/2" short carbide 4 flute cutter. Run the RPM up to 1200 or so and go to it.

Carbide chips easy so if you have slag on the cut you might want to use a rougher first and then finish with the carbide.

My Mill is a larger version of a RF 45 and I can get nice clean cuts in steel with smaller cutters.

It also does a good surface job too.

I did a little video of some surfacing.

[ame=http://www.youtube.com/watch?v=JMPjfdkN0vo]‪IH-facemill-bluechips115.MP4‬‏ - YouTube[/ame]

[hanermo]

You said you are taking off 1/10" or 0.1" (=2.5 mm) at a time from the edge ?
Try 0.01" - 0.02" - 0.03".

I suspect that you are vastly overloading the machine (rigidity wise).
Probably, a 4 flute endmill, 3-4 passes, will be faster, and leave better results.
Second the 0.5" inch cutter, I think 1" is just far too big for RF45.

[sgt panties]

OK thanks for the replies.

I bought most of my bits in one fel swoop as a lot on eBay. I suspect when some machinists meet their maker their heirs hock the lot on eBay. I got
some bits so pretty I'm afraid to use them. Take a look. Highly recommended.

I've always been cautioned not to be too timid when milling. I thought when one takes off too little it wears the cutter esp per unit of work done. Also steel is elastic so it bounces off the surface. Compelling theory. Don't know how true it is.

To the guy with the IH mill. Man, that is practically a different machine. They recast the whole column, 300 more lbs, IIRC, harden the gears, better bearings. I will try your suggestion about carbide though.

I've got to take a community college machine shop course if I ever get the time.

Cheers, all.