self-adjusting mechanism

[NicolasE]

hello

I have a trouble with a 96*48 shopbot
I'm making hexagon and when the x axle go back it make a mark that' s what I call a pursuit error on a "regular" cnc machine
it' seems like the right engine of the X bridge is looser than the left I had adjust with no result
I' really dont know where's probleme

could smeone help me please?

[barrowj]

Nicolas,

Not really sure what you mean but Pictures would help alot.

Joe

[NicolasE]

Hello John
sorry my english is a bit rusted
I'm cutting some polygone with a shopbot and I have a trouble
the bit plunge in the wood then the it cut in the -X +Y direction make the first angle after it goes full +Y then it change for a +X +Y direction when the X wagon change of direction the bit goes directly too far in the wood so it make a mark that I dont want

it's seems that music speak louder than words but pictures too :)
https://plus.google.com/photos/113007344134467452819/albums/6108665181052861681/6108665187433861682?hl=fr&pid=6108665187433861682&oid=113007344134467452819&authkey=CMOssNjX0oyRvwE
https://plus.google.com/photos/113007344134467452819/albums/6108665181052861681/6108665187972955986?hl=fr&pid=6108665187972955986&oid=113007344134467452819&authkey=CMOssNjX0oyRvwE
https://plus.google.com/photos/113007344134467452819/albums/6108665181052861681/6108665182817298850?hl=fr&pid=6108665182817298850&oid=113007344134467452819&authkey=CMOssNjX0oyRvwE

[Brady Watson]

Is this a PRT model or PRS model?

Are you talking about the spring on the motor mount, or ???

-B

[Brady Watson]

PRT:
http://fablabsf.org/wp-content/uploads/2012/10/shopbot-prt-96.jpg

PRS:
http://www.shopbottools.com/mproducts/images/products-PRS.jpg

[NicolasE]

a PRS one the biggest from Paris France!

[Brady Watson]

OK - two areas to look. First, you want to make sure that each pinion gear for each axis is tightly connected to the motor shaft. There are two 1/8" hex grub screws on each pinion that hold the pinion gear to the shaft. Second, each pinion gear must be properly meshed with the gear rack.

The Z axis is probably fine. Focus on X2 (front), X1 (back) and Y motors only. Remove the four 3/16" hex bolts from each and check tightness of the pinion screws using a 1/8" hex wrench. 3mm is NOT the correct wrench! The screws should be very tight - you may bend the wrench. This is OK.

Then, replace the motor and push the motor up so the pinion gear seats into the gear rack. This will take moderate force. While pushing up, tighten the 3/16" bolts. You may need to 'wiggle' the motor to get it to properly seat into the rack gear. Check your work. The Y axis is the most difficult.

Repeat this process for the other axes.

Also - inspect the pinion gears when you have the motor out. They do not last forever - they are consumable - and if they have been out of alignment, they are worn. You should order fresh pinion gears from ShopBot (get 2 sets) and replace. The long gear racks should have a thin coating of grease on them to reduce wear. When you replace pinion gears, your machine runs like new again - but pinions screws MUST be tight!

Good luck! Let us know how you make out.

-B

[NicolasE]

thank you very much Brady for your quick answer!!!
I check those adjustement and get back to you

[NicolasE]

It was exactly the trouble the pignonwas a bit loose I tight it and reput the engine in is place , the X car move without play it' s perfect

thanks again

her a pictures of the pignon it doesn't look bad but please ahave a look

https://plus.google.com/photos/113007344134467452819/albums/6108978132397694001/6108978135913354978?hl=fr&pid=6108978135913354978&oid=113007344134467452819

[Brady Watson]

Pinion looks fine - it still has black oxide coating on it - good!

I would still order a set to keep on the shelf for maintenance. Also - that pinion is dry - It needs to have grease on all 4 motor/gears on the machine. The Z axis is factory lubed.

You need synthetic axle grease. Use small wooden stick (bâton de glace) and apply a small ball of grease each 150mm along each gear rack. Then slowly move the machine back & forth to spread the grease. You do NOT want too much! You will repeat this for a few minutes and each stroke, wipe extra grease off with a rag. This will keep grease from dropping on your good work!

-B

[NicolasE]

the pignon was dry cos I clean before taking pics
I put grease on it before rebuild
I'm not coming from the wood I am a "regular" miller and I keep the moving parts well greased all the time it's my main obsession ;)

thanks again

N

[tlempicke]

Those pinion gears are so cheap that I make it a practice to replace when I am doing heavy maintenance on the machine. 20 dollars apiece.

Are you in France? We are coming there on vacation in August.

[NicolasE]

I will order some ;)
I'm sorry I didn't post any presentation may I make one her?

I'm Nicolas Ehrhart
I'm the workshop manager of the Usine IO in Paris France
the Usine IO is a new concept of fablab/techshop and so on
I't work like a gym club you pay every month and you have a school of 4 xperts in electronic/mecanique/CAD/production + a hudge workshop made of 5 spaces for every diciplines to help the developement of your project in a industrial perspective

you are gladly welcome to visit us !

http://usine.io/

[Brady Watson]

Nicolas,
It is nice to have you here. Welcome.

Yes - please feel free to post your project pictures and 'story' in the Show & Tell area.

-B

[adrianm]

I'd check to see if you can get the pinions locally rather than ShopBot if possible.

Not their fault due to the weight but the postage costs are huge to Europe.