MechMate CNC Router Forum

Go Back   MechMate CNC Router Forum > After Building the Beast - Operating , Troubleshooting and Maintenance > Troubleshooting
Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Reply
 
Thread Tools
  #31  
Old Wed 17 November 2010, 11:20
salewis
Just call me: Stan #67
 
Littleton, NC
United States of America
as for the string comment - I walked right into that one

After a long run last night, Ted thinks the screws have backed up... When I disassembled it yesterday, the screws had not backed up/out.

Gerald, your last comment has me thinking that the back/forth action on the z (we are doing a lot of 3d, especially z) is causing the shaft to "wallow out" where the screw contacts the shaft. I have seen/heard people relief drilling into the shaft before the set screw to give the set screw a bit of a shoulder to work on.

As for loctite, I've got some red (aka permanent or bearing mount).

BTW, this is on the larger gear (72 teeth) of the belt transmission. The pinion is holding solid. This gear is also Aluminum though we have a steel gear in our stash.

Back to the length of string is that before/after knots and twists? Besides string is either too long or too short, it is never just right. That is why we have teeth. (Just made Ted aka Crashingsucks crazy on that one.... )
Reply With Quote
  #32  
Old Wed 17 November 2010, 11:59
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Sorry, couldn't resist the string snark

If the metal/metal contact is "wallowing out", it can only help if you double the number of those interfaces.....a second screw hole.

A pre-machined hollow wouldn't be as good as a a hollow worn in by the screw itself. A couple of re-tightens in the early days should get the screw/s nicely bedded. Then add loctite.
Reply With Quote
  #33  
Old Wed 17 November 2010, 12:09
salewis
Just call me: Stan #67
 
Littleton, NC
United States of America
Yeah it is better to pull the string than push it!

I can see the point there on just letting it wobble a bit and retighten (using new screws).

BTW, we already have two screws 90 degrees apart
Reply With Quote
  #34  
Old Wed 17 November 2010, 12:47
jwt
Just call me: John
 
Wexford
Ireland
Aha!

This is where my cunning stunt of cutting the grub screws down and having a flat surface pressing against the flat on the shaft comes into play.
*cough*
Reply With Quote
  #35  
Old Wed 17 November 2010, 16:16
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Very educational thread.
John, I'll store your trick for later use.
Reply With Quote
  #36  
Old Wed 17 November 2010, 16:57
jwt
Just call me: John
 
Wexford
Ireland
You might want to wait until I try it out in anger so far it's all theoretical until the pinions get a hard workout
Reply With Quote
  #37  
Old Wed 17 November 2010, 18:14
salewis
Just call me: Stan #67
 
Littleton, NC
United States of America
on and similar but different wavelength (figure that one out guys.... )..

I fly R/C aircraft and we use a collar arrangement to keep (or at least supposed to keep) the wheels attached to the wire landing gear. Think small wire (0.125 or so) with brass collars and a single set screw (smaller than #2). Well a buddy and I got tired of his wheels coming off (due to collar falling off)....

So.. I took a collar rethreaded with a 4-40 and used an alloy/hardened socket head machine screw that I had cut off...

Similar to JWT's thoughts.... different application... but it might work. Especially if we ruin another $400 part.

But we are running even as I write this so I know more in about an hour....

stan
Reply With Quote
  #38  
Old Wed 17 November 2010, 22:51
salewis
Just call me: Stan #67
 
Littleton, NC
United States of America
Just got back from the shop. Recut of the mold.... Wait for it....

V
V
V
V

PERFECT!

Better than what the guy was getting from another guy running a ****bot

Just got to keep an eye on the set screws before running a 6.5 hour finishing pass.
Reply With Quote
  #39  
Old Wed 17 November 2010, 23:08
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Quote:
Originally Posted by jwt View Post
. . . . cutting the grub screws down and having a flat surface pressing against the flat on the shaft comes into play. . . .
That was the old-fashioned way and that style of grubscrew was notorious for working loose. The most popular screws today have a knurled cup at the end.

Reply With Quote
  #40  
Old Thu 18 November 2010, 06:55
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Quote:
Originally Posted by salewis View Post

Better than what the guy was getting from another guy running a ****bot
One of the main reasons why I went the MM route. Before the MM, I asked for and received samples of what other machines could cut. I was amazed how bad the cut quality was. And, that a company would send out something of such poor quality. Bad for them, good for me.
Reply With Quote
  #41  
Old Tue 23 November 2010, 09:20
liaoh75
Just call me: David
 
Taibao
Taiwan
I get better cut quality than a large number of CNC machines manufactured in Taiwan in the $15,000 to $20,000 US dollar range. Of course the $50K to $100K Big Iron machines cut about the same as the Mechmate. I've seen a number of big iron machines around here sporting a lot of bells and whistles like massive servos and 55mm lead screws, but I'll have to say that I'm really not jealous. I've even seen 5X10 machines go from x and y extremes to home in under 3 seconds (Yes, I've see a few that could actually pull that off and it is really impressive) but, can you really cut at that speed? No!!!
Reply With Quote
  #42  
Old Tue 23 November 2010, 11:36
salewis
Just call me: Stan #67
 
Littleton, NC
United States of America
Yeah, I mean come on folks... Why pay that when for less than $5-6K one can get this quality of cut....

Our silent partner in the process uttered a quiet "wow," when he saw the mold... He's pretty hard to impress....
Reply With Quote
Reply

Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
mechmate.com search - SOLVED !!! rotorzoomer Miscellaneous / General / Whatever / Catchall 4 Mon 17 May 2010 17:00
Pinion gear chatter lunaj76 Driving Mechanisms: Rack/pinion, gears, screws, belts & chains 5 Tue 27 October 2009 01:29
Inconsistent accuracy - loose pinion gear bfauska Troubleshooting 11 Sat 05 September 2009 09:05
Screw threads - inch & millimeter Gerald D Golden Resources 1 Mon 09 March 2009 00:54
Circles are not cut round - loose pinion gears sailfl Troubleshooting 21 Sun 15 February 2009 17:19


All times are GMT -6. The time now is 20:55.


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.