Cut Motor Drive Cable

[David]

The Cut Motor Drive Cable on my machine rounded out the female shaft on the motor (go figure another design problem). Every time I try to do a project for a customer on this machine and make some money, it breaks and costs $$$$$. If I make something for myself it works fine. $140 for a new motor and $75 for a new cable + shipping. I am not going to do it, SO, I fixed it myself and saved the $, how, let me rant a little first. Designed by NASA engineers, the same ones that WHOOPS, designed the Dart Spacecraft, the Mars Observer, the Hubble Space Telescope, the Atlas-Centaur Rocket, Galileo, and I can go on and on (all failures by the way).
The Fix! I took motor and shaft out, let the cable stick out the front of the insert shaft 1/2" and temp. taped into place. cleaned both the slot/shaft in the motor and the end of the cable that fits in it extreamly well with acetone. I then used JB Weld on both parts being very carfull not to let oozz out, then, secured the shaft in place as it normally goes (and put the little screw in that holds it in place) and let dry for a day. 12 hours now on the machine no problems. If it does come loose, I'll just redo it. Maybe NASA should hire me!

The Man Who Hates This Machine (but still uses it)

Dave

[lawrence]

Thanks for the how- to- it is very much appreciated and is well spelled out

Little harsh on the NASA thing don't you think?-- no one else in the world takes such large risks-- therefore some of the near-successes are quite spectacular. None the less, they designed a machine that is similar-- great things that no one else can come close to duplicating (for anywhere near the $$) but sometimes the failures can be quite dramatic and sudden. I for one, am proud to support both-- NASA and LHR-

Once again though- very nice job on the instructions-- if I ever have a similar problem I may use it- but for now I haven't had any issues. (knock on wood)

Lawrence

ps- not too shabby a pic from Hubble!

[David]

Lawrence,
Yes, NASA has done spectacular things, and I do support them, we have two jets that race in the Reno Air Races and have built 9 of the jets that race (we hold the course speed record and have first place finishes the last 3 years) and our #1 pilot Kurt Brown is a 6 time shuttle pilot (one of only two that have flown 6 missions. 3 in the right seat and 3 in the left seat). Mainly just venting and also just pointing out, just because it was designed by NASA dosen't mean its cost effective, durable or built for long working span. Their successes very much outweigh their failures.

Dave

[gregsolano]

Good fix but make extra sure you keep flex cable properly lubed since a flex cable failure would be really hard to fix since the flex cable is now permanently attatched.

[David]

Greg,
10-4 but, the only way to fix it anyway was to replace motor $140 and flex shaft $75 plus all the shipping. At the least, I bought time (10 hours so far).
Dave

[gregsolano]

I fully understand, hope it lasts years.

[mtylerfl]

...The Fix! I took motor and shaft out, let the cable stick out the front of the insert shaft 1/2" and temp. taped into place. cleaned both the slot/shaft in the motor and the end of the cable that fits in it extreamly well with acetone. I then used JB Weld on both parts being very carfull not to let oozz out, then, secured the shaft in place as it normally goes (and put the little screw in that holds it in place) and let dry for a day. 12 hours now on the machine no problems. If it does come loose, I'll just redo it. Maybe NASA should hire me!
...Dave

Hi Dave,

Sorry you had the problem with the flex shaft. I want to clarify what may have led to the problem and how you can avoid it in the future...

That particular problem was most likely caused from not having one end or the other fully inserted into the square receptacles (i.e., at the top hat or the cut motor end). This can cause two problems... one, it leads to overheating due to a "bunched" flexshaft causing excessive friction inside the rubber sheath...two, it will cause rounding of the shaft ends and/or the square-hole receptacles. It is easily avoided by just making certain the flex shaft ends are fully seated at both ends during installation.

I have some concerns for you regarding your "fix". The flexshaft core is intentionally designed to freely "float" about a half inch or so along the length between the top hat end and the cut motor end while it is running. The square receptacle holes are deeper than the length of the flexshaft, and that is what permits the floating. Again, this is intentional, by design.

It is my understanding this prolongs the life of the flexshaft itself, as well as helping prevent overheating (in addition to proper lubrication). By "welding" one end of the flexshaft, it can no longer "float" as intended. I am not exactly sure what the repercussions might be for you, but I would keep a close eye on it. I am guessing it will lose its spring tension much sooner due to the additional stress it will undergo during use by not being able to float while running, and you may experience overheating even though you have lubed it. The CarveWright Techs could advise you much more accurately on what to watch out for.

Hoping this helps you and possibly others, as well.

[David]

Michael,
I do agree with all your comments. My reason for doing what I did is twofold. 1. in order to fix the problem and make the machine work again I needed to spend about $250 and wait for the parts. 2. I needed to finish a job for a customer quicker than waiting for the parts and the fix made that possible.
I do understand that at some point this fix may fail and I will need to replace the above parts but, I am getting extra hours and finishing jobs until the time comes
I must replace. I will keep an eye on this, but on a 4 hour run, the cable did not get any warmer than normal.
Dave

[mtylerfl]

Hi Dave,

Thank you. I understand, and am very glad it was able to get you going again for your 'client urgency'. As you say, just keep an eye on it and wait to see if anything further needs to be done in the future. All the best to you and thanks again.

[Digitalwoodshop]

Dave,

I think I would have drilled and tapped for a set screw...... That is just me.....

Ya the NASA Slam was un called for.... This Forum is all about Sharing in a Friendly Forum and Bullies get the Boot.... The Worst words used here are some TUFF LOVE to Suggest new users to read the Tips and Tricks to prevent the Pilot Errors that get posted over and over... We wrote the Tips and Tricks as we were all new once and did the same silly things over and over.... Tips and Tricks helps the New Users.

I see you have been a member since 2007 so you must have a nice collection of projects due to the Ingenuity of the NASA Engineers... I know I do and I joined in 2007. And I have the NASA Engineers to THANK.... That Shop Bot was 5 years away and with the Down Economy now, I would NOT have been able to buy it.... The CW actually SAVED my Business.... My Fire Tags and Boards are cut on the CW and without it.... Well, the Lights would have been turned off and doors closed about 2 years ago and I would be sitting in a Bar drinking a BEER.... Rather than that, I am in the Shop working at 9:30 PM on a Sunday Night, my CW just finished cutting a batch of Fire Tags.


AL