I love my Tormach, but...

[mike sr1]

I balanced the fan impeller, this made quite a difference.
I balanced the spindle and motor pullys as best i could.
The motor balance was relatively good bu itself.(no fan or pulley)
I use the Fenner belt, this helped with the noise and possibly some with a bit of vibration, if this belt is too tight it too will make noise as well.
I also do not lock the motor down tight, I am using a rigged belt tensioner, I am working on one that will keep the belt tensioned without the lockdown screw being tight, my theory is that it will isolate the motor vibration from the machine somewhat, what little there is left.

I would like to say that my machine is great for the money, I am not downgrading it at all. I didnt expect to get all the features of one that cost ten times as much.

[twocik]

I'm sorry it's hard to see the finish in your pics and was curious how does your finish compare to this ?












Here's the thread I started a while back

http://www.cnczone.com/forums/tormac...nishing-2.html



I've been trying to crack this nut for a long time and have gotten pretty close, but only a little better than what you see in that pictures. I've used more flutes, higher helix, different S&F, increased cutter dia., DOC, WOC, etc.. and can't seem to get the "streak" pretty clean cut as seen on high end machines. For the longest time now I wondered if it had something to do with the spindle or stepper motors. What I'm seeing is almost a frequency type pattern on my parts.

From the pictures this looks like a very nice clean cut finish, but it's hard to see without a close up flat lit picture. I would love to see more pics from different angles and close ups.




Do you have a link to the belt you bought ?




Good stuff, really enjoy threads like this !!!

.

[mike sr1]

ebay.com
fenner belt in the search if this link doesnt work.

I will take more pics, I have a canon t3I but dont have a closeup lens for it. I need to take them outside without flash, maybe sometime today.

The quality would be much better in an email as it wont let me post large pics on the forum.

I had basically the same problem as you do, the spindle balance was what made the improvement for me.

I have been finishing at max rpm now (aluminum parts) instead of picking an rpm to reduce the marks. In my opinion it was worth the time spent balancing.

edit: I used a set of harddrive bearings to make a static balancer for the fan, those spin very freely and it worked very well. I think the fan was the biggest culprit although it was the last thing I tried.

I also really enjoy these types of threads as long as they dont turn negative.

[nitewatchman]

Power Twist Plus Link V-belt 3/8" 3L 4' FENNER DRIVE | eBay

[tbaker2500]

twocik, it kinda looks in the pictures like the poor finish is only in the corners, is this correct?

[mike sr1]

These are two at full resolution but cropped back, so the area in question should be good quality other than the lighting etc, it kind of shows at the left end of the samples.

doc was approximately .010
cutter .5 reground (not a quality grind)
flank cut about .375 or so
max rpm (5100)
4 flute cutter
length of flutes about .625

The samples to the naked eye look very good from 40 ipm on down at 5100 rpm
These were cut dry, no oil or coolant.
If I had a better grind on the cutter they would look better.

Edit:
I checked the 30 ipm at 5100 rpm with a 10 x loupe, it looks very good no matter which way the reflection/lighting is, i cant say the same about the horizontal marks from the cutter though ha!

[mike sr1]

I am new to cnc machining but I have used the Bridgeport for years, my theory is to use as large diameter as practical and as short as possible cutters, the more flutes the better for finish, the diameter and length for rigidity.

This is just my opinion.

[TurboStep]

twocik,
I can't say much about your first picture because you didn't specify the spindle speed or feed rate. It looks like it could be, but if you could specify the info then we should be able to confirm this.
Knowing from an earlier post that the end mill is 1/2" I roughly estimated from the photographs that the pattern has about 120 "marks" per inch. With 2500 rpm and 25 in/min you will have 100 spindle rotations per inch. These two values appear to be close enough to indicate that these are actually cutter marks and that only one flute is doing the final cutting. I think this is quite normal because I estimate that the total runout would need to be below 0.0001" (calculated from your end mill size and feed per rotation) in order for you to benefit from multiple flutes - which is probably why you don't see an improvement with 4 flute cutters. I'd be interested if anyone could confirm this.
If this effect were due to the vibration problem then you would see only about 20 "waves" per inch under these conditions.
To improve on this finish you would either need to get the runout right down, which is difficult, especially if you have an ATC, or to up the rotations per unit of travel. Slowing the feed will obviously make finishing painfully slow but increasing the speed may introduce the vibration effects.
From my experience the Fenner belt doesn't improve the finish but it does reduce the noise slightly. This is a subjective opinion as someone has already mentioned that there are some annoying, higher frequency components. I guess it just depends how old you are I'm old enough so I'm leaving it on my mill.
Step

[twocik]

Hi Mike I'll free up my PM box now, shoot me your email. I'd really like to see exactly what you've made/fixed and the higher res pics... Still very hard to tell not at full res and without a macro. I think CNCZONE down res every pic to save on upload space.



nitewatchman Thanks for the link




tbaker2500 No same finish shown on the whole part at the time, this is another problem with taking pics of shinny AL....



"I am new to cnc machining but I have used the Bridgeport for years, my theory is to use as large diameter as practical and as short as possible cutters, the more flutes the better for finish, the diameter and length for rigidity.

This is just my opinion."



I totally agree and do for most jobs. This was just a test I did about a year or two ago to find the best finish possible with the lot of 2 FL ZRN carbide cutters I bought at the time. I have tired more flutes, shorter bits, etc.. all seems to be about the same finish. Don't get me wrong I've gotten very good results off the table, but requires a little more finishing to bring them to my part standards. After adjusting many things on my machine (can't remember all, it's been awhile) I still see the little vertical lines at the right angle in my shops light, but have developed a process to remove them and maintain the same quality, tolerance, etc... Just takes much longer




TurboStep Hi Turbo I posted the link, but not all of the information from it. All pics shown were at the cutting information you see in the one picture. I have spent a great deal of time to get my machine within spec once it first arrived and more time to bring that even further. I have noticed at 9 - 12 IPM it's vibrates very hard and took a day off to figure some sort of honey spot (thread I created) for a finish. I spiral rough cut leaving a .015 - .02" for finishing (3 way nozzle flood coolant). At full DOC I finish at 2500 rpms, 25IPM. I can't remember exactly what my RO was at the spindle measuring the tool shank, but wouldn't hurt to do so again. I'll report back after I measure.

[philbur]

Do you have the 3 phase stepper motors fitted:

Direct Document and Software Download | Tormach LLC | We provide personal small CNC machines, CNC tooling, and many more CNC items

Page 11 onward.

Phil

I have noticed at 9 - 12 IPM it's vibrates very hard and took a day off to figure some sort of honey spot (thread I created) for a finish.

[twocik]

Phil still using series II motor.... Have you seen a difference using III ?





I was able to cut a quick test part and here are the vertical and frequency lines I've been talking about. Same S&F, DOC, WOC, Tooling, etc...

[TurboStep]

twocik, sorry for not responding earlier. First of all, cutting at 2500rpm appears to be well below the problem range. Your latest photos show a pattern at approximately 115 lines per inch which is close to the 120 marks per inch that I estimated in a previous post. Again, this corresponds to the spindle speed and is likely to be cutter marks from the one flute that is taking the final skim off the surface. If you were having the problem that I have been describing then you would only see about 20 marks per inch with this speed and feed combination. Another point to look out for is that these more widely spaced marks would have a constant width across the full length of the cut and around a boss. If you see wider marks but not of constant width then its probably due to chatter.
The zig-zag line is quite interesting. If you determine the position on an end mill/holder with the most runout i.e. the where the cutter swings out the most, and imagine a straight edge pressed against the flutes you will see that more than one flute will be usually be resting on this edge. Although only one flute is likely to be taking the last skim off the surface, as we move up the face another flute will take over. My theory is that this zig-zag line is the border between two such areas. If you look carefully at the vertical lines above and below this border they are not inline. This indicates that they were not cut at the same time which would also imply that they were cut by a different flute. It's a nice example of an effect that I have seen before but these all appear to the the results of a mechanical cutting process. In my opinion this is about as good as you can probably get without either increasing the speed or reducing the feed.
Step

[riabma]

Hello to everybody,

After all this time, I decided to put again my machine for sale. Reduced price with a ton of tooling, gages, etc... If somebody is interested in please send me a PM.

Ricardo

[FannBlade]

What state are you located in?

[riabma]

What state are you located in?

The great state of Texas.
Houston area

[mike sr1]

I installed my power drawbar today, it has been sitting for over a year, I was dreading the ballance thing again, I had good reason to as when I started it up and ran the rpm to max it had a lot of vibration in the spindle, turns out though that I have it reasonably well balanced with the addition of one radiator clamp strategically placed ha! It isnt quite as good as before, I would say its about 90 percent now.

I do need to come up with something more professional than the radiator clamp but it does work.

[philbur]

My standard manual drawbar caused some vibration on my mill due to being out of balance. I found that the hole in the top of the spindle was considerably larger than the diameter of the draw-bar, so the draw-bar axis would usually not line-up to be concentric with the spindle axis when tightened. I installed a small bushing in the top of the spindle bore to reduce the effective diameter which centralised the draw-bar, then everything was fine.

If a draw-bar arrangement is symmetrical about its axis and is well centralised in the spindle I don't think it would create balance issues at < 5,000 rpm.

Phil

I installed my power drawbar today, it has been sitting for over a year, I was dreading the ballance thing again, I had good reason to as when I started it up and ran the rpm to max it had a lot of vibration in the spindle, turns out though that I have it reasonably well balanced with the addition of one radiator clamp strategically placed ha! It isnt quite as good as before, I would say its about 90 percent now.

I do need to come up with something more professional than the radiator clamp but it does work.

[mike sr1]

I installed my power drawbar today, it has been sitting for over a year, I was dreading the ballance thing again, I had good reason to as when I started it up and ran the rpm to max it had a lot of vibration in the spindle, turns out though that I have it reasonably well balanced with the addition of one radiator clamp strategically placed ha! It isnt quite as good as before, I would say its about 90 percent now.

I do need to come up with something more professional than the radiator clamp but it does work.

I just lost my reply??

I have since made eccentric rings to balance the spindle nut, and get rid of the radiator clamp ........
I checked the noise on the Fenner belt and its really not objectionable, to me anyway, it was originally though and when really tightened it was really bad, not so now, maybe its wearing in a bit??
I have been using the belt maybe 6 months.

[GJeff]

We'd love to see a pic of your eccentric ring setup if you get a chance. Sounds like something we should all consider doing if it's not too tough.

[nitewatchman]

We'd love to see a pic of your eccentric ring setup if you get a chance. Sounds like something we should all consider doing if it's not too tough.

+1