WMD30/BF30 belt drive to 5000RPM - Page 4


Page 4 of 5 FirstFirst 12345 LastLast
Results 61 to 80 of 88

Thread: WMD30/BF30 belt drive to 5000RPM

  1. #61
    Member LongRat's Avatar
    Join Date
    Apr 2005
    Location
    UK
    Posts
    861
    Downloads
    0
    Uploads
    0

    Default

    I never run above 3600 as stated above. I have done quite a bit of cutting since then, and a couple of longer runs. With the quill extended it seems to get a lot hotter (way too hot to touch the lower bearing area). I wasn't too comfortable with that, but I don't like having to run with the quill extended anyway. The stock bearings are holding up ok though and I haven't changed them. I would not be comfortable going any faster than I am now on the stock bearings.

    LongRat
    www.fulloption.co.uk


  2. #62
    Registered
    Join Date
    Jan 2010
    Location
    UK
    Posts
    84
    Downloads
    0
    Uploads
    0

    Default

    Thanks for the reply longrat.

    I certainly want to go with a replacement motor similar to yours. However I think I would like to repalce the bearings even if its just to help me sleep at night!.

    Having not dismantled the head do you think this will be hard? Will I have trouble getting the bearings off the spindle? Am I really wasting my time (and cash) with the replacment idea and better just living with 3600rpm.

    Have you connected the vfd to mach3? Will it allow for auto reverse (tapping etc?)?

    I have managed to run my Wiess machine cutting delicate parts for about 5 hours, no problem. Yet this was only doing 2250RPM and yes the quill was very very hot!

    A



  3. #63
    Member LongRat's Avatar
    Join Date
    Apr 2005
    Location
    UK
    Posts
    861
    Downloads
    0
    Uploads
    0

    Default

    I don't know how hard it would be to remove the bearings. It doesn't seem like it would be that difficult, Digits may have a better idea as he has had his apart.
    The biggest problem with the heat is spindle growth. I am seeing my cuts deepen due to thermal expansion, and it is noticeable. I haven't measured it but by eye I would say at least 0.050mm. On my last long run I pre-warmed the spindle with a full speed run for 10 mins before I started the program. This is very annoying.

    LongRat
    www.fulloption.co.uk


  4. #64
    Registered
    Join Date
    Jan 2010
    Location
    UK
    Posts
    84
    Downloads
    0
    Uploads
    0

    Default

    Thanks for the reply, however some questions


    Is spindle expansion through the use of the wrong type of steel or is it another inherent issue of a Chinese mill? Would some form of cooling help (similar to a water cooled pc). If I had a new spindle made of high quality steel (ground by a 5 axis hurco vmc) would this help? Or is it not the biggest problem with the head and there are other issues. Would replacing the head altogether be a solution? Suppose the problem is what do you replace it with! on the other hand with backlash of .2mm would an extra 0.05mm be a big issue?

    When I ran the machine for 5 hours I was doing a simple engraving so I would not notice an increased depth. However I did notice the spindle heat without having to touch it, I left the cutter in there till morning before releasing and not surprisingly it was still warm then!

    Sorry for all the questions however its probably best to have all the info to hand to make sure the money goes in the right place!

    A



  5. #65
    Member arizonavideo's Avatar
    Join Date
    May 2008
    Location
    USA
    Posts
    1185
    Downloads
    0
    Uploads
    0

    Default

    The tapered roller bearings just make a good amount of heat. It does not help that their is that huge ball bearing up top with seals that make a lot of heat too. You could lower the pre-load ever so slightly. I found my big mill had loose bearings and I tightened them up and they are a bit tooooo tight and I have lots and lots of heat on my RF-45 mill now.

    A/C will lower the heat and if you plan on doing a lot of high RPM work then that is the way to go.



  6. #66
    Member LongRat's Avatar
    Join Date
    Apr 2005
    Location
    UK
    Posts
    861
    Downloads
    0
    Uploads
    0

    Default

    I agree with what Arizona has said. Lots of high RPM work for long periods would point to AC bearings. In fact I would probably go for them regardless if I was looking to replace the bearings. Taper rollers are not rated to much above the speed I am running at, in fact at this size I am very close to the limit if you go by NSK ratings (and I bet the bearings in the Weiss are not high quality NSKs either).
    Spindle growth is something to watch out for in any milling machine in my experience. There's nothing inherent in the Chinese spindle that makes it a problem there only. High end spindles are cooled so this issue is hugely reduced. Regardless of your backlash, it WILL make a difference because it will affect the repeatability over a run. I have 70µm of z backlash but the repeatability is probably 10 times better than that. As such my z backlash is only a problem when continuous contouring in all 3 axes.

    To sum up, the spindle will grow if it gets hot. You can cool it with a jacket as one solution, or you can remove the heat source as another. This could be by reducing the preload or fitting better bearings, such as angular contacts, which produce less heat. For a mill like this I wouldn't worry about anything too complex as a solution. If you replace the bearings please post a thread as I don't think there is anyone on here who has done it on a BF30.
    One more point. My system gets very very hot when run for over 15mins when the quill fully extended. Less hot with it retracted (see my graph previously posted). But if you are leaving yours to sit overnight and the mill is STILL warm, I would be concerned. You are in that case getting MUCH hotter than I am, or you live in an oven.

    LongRat
    www.fulloption.co.uk


  7. #67
    Registered
    Join Date
    Jan 2010
    Location
    UK
    Posts
    84
    Downloads
    0
    Uploads
    0

    Default

    Thanks for the replys, interesting information. I have just looked at the SKF angular contact bearings and they start at about £40 and run to £100's. I dont mind spending £200 on a bearing if it is a major fix to the spindle overheating.

    However I think if I go that route you may as well replace the others...ok I will do some reading and see what ac bearings are best, I will also ask some people at work that do this all day!

    I also see if I can find digits to see how he got the spindle out and if it was a real pig

    Cheers,

    Tef



  8. #68
    Member arizonavideo's Avatar
    Join Date
    May 2008
    Location
    USA
    Posts
    1185
    Downloads
    0
    Uploads
    0

    Default

    I looked at Grizzly web site on the 704 mill and they list the bearing as a 32005.

    My Weiss 30 has the exact same exploded view but has no bearing #.

    It looks to be a common rear axial bearing. Hoss had the size listed somewhere.

    You don't need a fancy grade of A/C bearings just a good quality SKS or NSK will be fine and cost around $30.00.

    I don't know the best contact angle for spindles. The two most common are 15deg and 40deg.

    Someone should know this. I think its 40deg.



  9. #69
    Banned
    Join Date
    Mar 2009
    Location
    USA
    Posts
    1114
    Downloads
    0
    Uploads
    0

    Default

    I have a PM25MV from Precision Matthews which I'm pretty sure is a Weiss WMD20LV and it has NSK spindle bearings.

    Upper 52x28x16mm 7100 RPM with grease
    Lower 62x35x18mm 6300 RPM with grease

    The G0704 bearings are different in size and performance.



  10. #70
    Member LongRat's Avatar
    Join Date
    Apr 2005
    Location
    UK
    Posts
    861
    Downloads
    0
    Uploads
    0

    Default

    That pretty much proves the fact that if brand X has good bearings it doesn't mean that brand Y of the same machine will have those bearings. You also have to be a bit careful with Chinese bearings, as it is known for many to come out of factories laser etched with high-end Japanese branding even though they were not made by those companies.

    LongRat
    www.fulloption.co.uk


  11. #71
    Banned
    Join Date
    Mar 2009
    Location
    USA
    Posts
    1114
    Downloads
    0
    Uploads
    0

    Default

    I was not aware of this branding issue. I'm not sure what kind of laws they have over seas but I'm sure you could get in some serious trouble here in the states if you attempted a stunt like that.



  12. #72
    Member LongRat's Avatar
    Join Date
    Apr 2005
    Location
    UK
    Posts
    861
    Downloads
    0
    Uploads
    0

    Default

    I'm not saying that these mills have such bearings in them of course, just that it is possible and does happen. Check this site: Stop Fake Bearings World Bearing Association / Start

    LongRat
    www.fulloption.co.uk


  13. #73
    Member arizonavideo's Avatar
    Join Date
    May 2008
    Location
    USA
    Posts
    1185
    Downloads
    0
    Uploads
    0

    Default

    A quick search found hoss saying "The upper is 25 x 47mm, the lower is 35 x 62mm "

    I forgot but the A/C bearings are shorter so you need to make a spacer so the nut will give preload.



  14. #74
    Member LongRat's Avatar
    Join Date
    Apr 2005
    Location
    UK
    Posts
    861
    Downloads
    0
    Uploads
    0

    Default

    Yes but I thought he had the G0704, smaller than the BF30?

    LongRat
    www.fulloption.co.uk


  15. #75
    Banned
    Join Date
    Mar 2009
    Location
    USA
    Posts
    1114
    Downloads
    0
    Uploads
    0

    Default

    You are correct



  16. #76
    Member arizonavideo's Avatar
    Join Date
    May 2008
    Location
    USA
    Posts
    1185
    Downloads
    0
    Uploads
    0

    Default

    Who is correct?



  17. #77
    Banned
    Join Date
    Mar 2009
    Location
    USA
    Posts
    1114
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by LongRat View Post
    Yes but I thought he had the G0704, smaller than the BF30?
    He is correct. Sorry I forgot to quote it.



  18. #78
    Member
    Join Date
    Aug 2006
    Location
    UK
    Posts
    1602
    Downloads
    0
    Uploads
    0

    Default

    Hi LongRat - what sorts of speeds and feeds can you run with your AC motor? I am trying some 3D stuff with 10-12mm cutters, and while it's fine when cutting horizontally, the stock motor really seems to be struggling on plunges.

    I am getting tempted to do a VFD conversion myself...



  19. #79
    Member LongRat's Avatar
    Join Date
    Apr 2005
    Location
    UK
    Posts
    861
    Downloads
    0
    Uploads
    0

    Default

    The hardest I have pushed it is 5000 RPM, 5mm depth of cut at 500mm/min in aluminium. That's with a 10mm 2-flute carbide tool. Air blast cooling.
    I run a tacho linked to Mach3 so I can monitor the spindle speed in real time. I never see any significant bogging in spindle speed, but generally I'm using 8mm cutters and under so I'm really more interested in the speed than the outright horse power. Needless to say, I definitely think the 1.5 HP motor is the right way to go for the BF30. The pulley ratios I have set up are great for what I need, including slitting saws and fly cutters in the 4" diameter range. I think if you wanted to do a lot of steel work with larger tools and use the variable speed a vector drive would be worth the extra cash as you wouldn't lose as much torque when slowing the motor shaft speed.

    LongRat
    www.fulloption.co.uk


  20. #80
    Member
    Join Date
    Aug 2006
    Location
    UK
    Posts
    1602
    Downloads
    0
    Uploads
    0

    Default

    On the stock motor I've been cutting at 1-2mm DOC, 80%-100% WOC on 10-12mm cutters at 700-900mm/min. I'm using 3 and 4 flute roughers, which simply destroy aluminim while cutting horizonatly, but seem to deflect rather badly during plunges.

    I was wondering whether a higher rpm would increase my plunge rate - I don't want to have to back the whole job off to <100mm/min as it takes 3+ hours already!

    I've been looking at the prices of VFD's - a 1.5HP Vector drive looks to be about the same price as a 2HP servo-drive, but obviously the servo motor to go with it is more expensive - about £100 more than a 1.5HP 3-phase.



Page 4 of 5 FirstFirst 12345 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

WMD30/BF30 belt drive to 5000RPM

WMD30/BF30 belt drive to 5000RPM