Flex in the mill spindle.

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Hi guys and gals.
So I finally got my Chinese ZAY7045V/1 to the point where I can begin to try to mill something but I can't seem to be getting any results. I tried milling some mild steel, just to learn how things work. I had a 16 mm HSS endmill in a ER25 collet and tried to slot mill the steel. 0,2 mm depth of cut gave terrible vibrations at 500 rpm and kind of crappy finish. Anyway after lots of trying onething and learning something else and repeating several times I decided to test the runouts on the ER holder and the endmill, results were 0,05 mm runout on both which seemed reasonable since they are from China. But after that I stuck the dial indicator to the spindle and tried how much give it has when pushed and pulled and the result was 0,1 mm. How screwed am I, this seems too much, is there anything to fix this?
 
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That *is* quite a bit of deflection, but the important thing at this point is probably to see how much it affects your actual machining.

A couple thoughts:
1. Is the quill / spindle extended? Retracting it should make the setup more rigid.
2. Do you have spindle locks? If you are able to, locking the spindle before milling should help.
3. 0.2mm is pretty light - I'd be running higher rpm for such a cut, especially if you're hand feeding. Try 0.6mm depth of cut (as a starting point) and see what happens.
4. "mild steel" is a little unclear, but if it's 1018 or the like, it can be tough to get a good finish regardless of the machine. If you have some 12L14, aluminum, or 4140 those should all finish nicely with proper speeds and feeds.

HTH,
GsT
 
Thanks for the reply.
1. That measurement was done quill fully retracted.
2. I think I do, is that the lever that locks the up/down adjustement? If so, that was locked too.
3. I tried side milling today, depth of cut into the part was 1,5 mm, rpm at 420. Vibration was lesser, but the quality was frankly crap.
4. The stock I have is just some scrap from recycling, off-cuts from machine shops etc. So I have no idea what grade those are.

The biggest problem is as I'm a total newbie into milling, I have no idea if the problem is the machine, material, endmill quality, speeds, me or something else. So I'll have to start eliminating so possibilities:
I'm using these as a reference for speeds, could anyone give an opinion whether these are even close to what I should use? https://www.etantdonnes.com/MACHINE/TABLES/cuttingSpeeds.html
 
I would spend some time milling aluminum first. Steel is worlds different & stresses the machine to its limits as far as rigidity and power.
16 mm endmill is large for a light hobby machine (if that's what you have)- try something smaller like 8mm or 6mm
The fit of the quill in the head is often somewhat loose on chinese machines. Lock it down if possible when milling.
If you can get HSS endmills with cobalt they are a good investment- they are tougher and stay sharp longer, for only a little more $$

Don't try to mill slots to size in one operation- the chips get trapped and re-cut leaving a terrible finish. Use 2 or 3 flute mills for slots, not 4
and use an undersized mill first to rough cut the slot, then finish cut to size. Stop and brush out the chips frequently.
Always use a cutting fluid or oil when milling steel. For aluminum you can use a light solvent like wd-40 or mineral spirits. Brass can be cut dry.
Ignore the speed charts and just go slow until you get some experience. Learn the difference between climb cutting and regular cutting.
When the machine is cutting nicely it will tell you thru the handles.
 
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markba633csi said:
I would spend some time milling aluminum first. Steel is worlds different & stresses the machine to its limits as far as rigidity and power.
16 mm endmill is large for a light hobby machine (if that's what you have)- try something smaller like 8mm or 6mm
The fit of the quill in the head is often somewhat loose on chinese machines. Lock it down if possible when milling.
If you can get HSS endmills with cobalt they are a good investment- they are tougher and stay sharp longer, for only a little more $$

Don't try to mill slots to size in one operation- the chips get trapped and re-cut leaving a terrible finish. Use 2 or 3 flute mills for slots, not 4
and use an undersized mill first to rough cut the slot, then finish cut to size. Stop and brush out the chips frequently.
Always use a cutting fluid or oil when milling steel. For aluminum you can use a light solvent like wd-40 or mineral spirits. Brass can be cut dry.
Ignore the speed charts and just go slow until you get some experience. Learn the difference between climb cutting and regular cutting.
When the machine is cutting nicely it will tell you thru the handles.
Click to expand...
Yeah, I will try with some plastic and aluminum tomorrow and with a smaller endmill, lets say 8 mm. What speed and depth of cut would you recommend? My mill goes up to 2600 RPM if I remember correct, the chart I posted above says around 3600 RPM for aluminum and max 2 mm depth of cut with an 8 mm end mill. Maybe slot milling was the wrong thing to call what I was doing, I was just trying to take some material off from the top off the part.
Will probably also have to invest in a set of quality endmills as I only have two HSS sets from China and set up the coolant system. I estimate that about 85 % of stuff I need to do with the mill is to steel, 10 % to aluminum and 5 % plastics or brass, so it would be great if I could at least mill steel with ok surface finish without massive vibrations. Also about 90 % of the stuff I plan to make isn't super tight on the tolerances, so it really is a hobby mill, but I've seen on youtube people with even smaller benchtop mills machining steel much better than what I'm able at the moment, even without coolant or oil, so I'm a bit puzzled.
About locking the quill, I think I've always done that (if that is done with the circled lever in the picture below).

1727018878564.png
 
Don't try to take more than about 0.5 mm (about 0.020") at one time in steel. If you get too much vibration take less.
Keep the spindle set at it's lower speeds for now, a few hundred rpm, until you get familiar with how the machine behaves.
Ignore the speed charts initially- they are mainly for production shops that need to turn out parts as fast as possible to make money.

Chinese endmills are often of poor quality. Good endmills cost $$ but they are worth it. Germany and USA are good. Poland also
Make sure the gibs on your table are snugged up as much as possible while still allowing smooth movement with some resistance.
You want as little play and looseness as possible in all the slides
 
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I don't think I've ever run across a good Chinese HSS endmill. However, I have run across quite a few good Chinese solid carbide endmills. With solid carbide you could use some of the higher RPMs your machine is capable of. Chinese brands that I've had good results from are "Speed Tiger", Shapro, and Oxolotl.ct - I got all those from Amazon.

In order of importance, I'd try finding some known material that you know can get a good finish. Even aluminum for test purposes, but since your interest is primarly in steel, I'd look for some 12L14, 303 SS, or 4140. Then start looking for better cutters. A small quality solid-carbide endmill shouldn't be too expensive. Keep going with face-milling. Side milling will almost always leave a lesser finish though there are some high-helix endmills that make it quite a bit better.

In addition to snugging up (or adjusting) your gibs, make sure your vise or workholding is solid. Lock any axis you are not using (e.g. when making a cut with the Y-axis, lock X & Z). And that is the quill lock you indicated, so you've been doing that right.

Stick with it, you should be able to get something. Pictures would help too - just to make sure that your definition of "crap" is reasonable.

GsT
 
markba633csi said:
Don't try to take more than about 0.5 mm (about 0.020") at one time in steel. If you get too much vibration take less.
Keep the spindle set at it's lowest speed for now, a few hundred rpm, until you get familiar with how the machine behaves.
Ignore the speed charts- they are mainly for production shops that need to make parts as fast as possible to make money.

Chinese endmills are often of poor quality. Good endmills cost $$ but they are worth it. Germany and USA are good. Poland also
Make sure the gibs on your table are snugged up as much as possible while still allowing smooth movement
You want as little play and looseness as possible in all the slides
Click to expand...
Now this is what confuses me, first respose was that 0,2 mm was a light cut and I should try 0,6 mm and faster rpm, you suggest lower speed and max 0,5 mm cut. Probably both can be correct for the person giving the advice but for me both don't seem to be right. Have to just try which one works.

Can't seem to find any brand name endmills from Finland, at least from a fast google search, all shops that sell to private customers seem to sell the same stuff as Aliexpress that I already have.

I also tightened the gibs as much as possible with a screwdriver, if I want to tighten them more I'll have to use a ratchet wrench.

GeneT45 said:
I don't think I've ever run across a good Chinese HSS endmill. However, I have run across quite a few good Chinese solid carbide endmills. With solid carbide you could use some of the higher RPMs your machine is capable of. Chinese brands that I've had good results from are "Speed Tiger", Shapro, and Oxolotl.ct - I got all those from Amazon.

In order of importance, I'd try finding some known material that you know can get a good finish. Even aluminum for test purposes, but since your interest is primarly in steel, I'd look for some 12L14, 303 SS, or 4140. Then start looking for better cutters. A small quality solid-carbide endmill shouldn't be too expensive. Keep going with face-milling. Side milling will almost always leave a lesser finish though there are some high-helix endmills that make it quite a bit better.

In addition to snugging up (or adjusting) your gibs, make sure your vise or workholding is solid. Lock any axis you are not using (e.g. when making a cut with the Y-axis, lock X & Z). And that is the quill lock you indicated, so you've been doing that right.

Stick with it, you should be able to get something. Pictures would help too - just to make sure that your definition of "crap" is reasonable.

GsT
Click to expand...
I'll upload a pictures of the piece tomorrow. I also tried a 16 mm carbide end mill which did cut better but vibrated a lot. Will try tomorrow something else.

I did lock the axis' that weren't used which lessened the vibrations but not nearly enough.

About the material sourcing, there aren't many places in Finland to get steel or aluminum for a private customer as most wholesalers don't sell to a private customer, only to business' and those that do, seem to only have S235JR structural steel, 304/316 stainless and AW-6082 T6 aluminum for sale. Also the amount of possible sources are few, in a 50 km range there are two companies that sell to customers that I know of and only one sells less than a full bar (3-6m) and they have only the materials mentioned above. So I would need to buy from another country, for example from stahlhaus24 seems to have a good selection which I will definately be using when I have a project that requires lots of machining but at the moment I need to get by with what I have as the minimun postage fee seems to be around 26 € for a 250 mm piece of 15x15 free cutting steel that itself costs 6 €, so I would need to buy lots of materials to make up for the postage costs.
 
For sourcing material are there any jobber machine shops in your area? Often if you get to know the guys there you can ask to buy offcuts (don’t call it scrap) at a reasonable price.

Also, does eBay work there? Lots of sellers on there so at least some of them should be willing to ship to you.

Finally, I know you’re not our only member from Finland. Try reaching out to @Mauzinette or @Norppu

John
 
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