[Ravi]

I have a wood shop, planning to buy a CNC router
I need a machine which should be reliable and holds tight tolerance.

Application: Cutting MDF and Acrylic sheets


Can some one advise which machine is the best? from the follwoing list

Or any other machine builder that you can recommend??


-Shopbot-->Shopbotools.com
-Shopsabre--->shopsabre.com
-Practical cnc-->Practicalcnc.com

Thanks for the help
Rav

[Ravi]

It seems form the other threads which I didn't read before

Shopbot seems the best

My questions is that

Is this machine is good for serious production????

[rboeser]

I built a shopbot where I used to work. It was a 4' x 8' working area if memory serves. I do remeber using a 5' x 10' mdf for the table.

It cut plywood great. The software at that time left atlot to be desired. I could not get it to cut aluminum if my life depended on it. I even had an "air cool" blowing on the carbide endmill.

I think you would have to define "serious production" before I would recomend it.

I put limit and home switches on it. Added a vacuum motor to it that would almost run you out of the shop when it ran. It did however hold wahtever you wanted to cut.

I remember it "racking" a few times also. After the many failed attempts at cutting aluminum, we placed it in the warehouse for "future" use. I'm certain it still remains there.

[Ravi]

thanks rboeser

Applications are (1) cut - 8" Dia round disks in 1/4" acrylic and 3/4" MDF (2) Drill holes in extrusion.

most of the time i will be using 4' x 8' sheets.

Serious production means If i have to cut 1000 parts will the 999th part be within tolerance.

Thanks again

[rboeser]

All I can tell you is call the shopbot factory. Give them the tolerance you expect and material specs. Get them to stand behind it if it wont do as they claim.

Best of luck!

[ger21]

I don't think a router would be a good choice for holes in extrusion, due to the high spindle speed. Maybe if you get a Columbo spindle that will run a little slower.

[Ravi]

Thanks ger21

i am not concerned about the spindle speed
will the hole position going to be same on all the parts??

thanks

[rboeser]

I do not know the answer to that question, sorry. I would call shopbot and ask them.

[ger21]

ShopBot states a postional accuracy of plus or minus .005, so it could be off as much as .01 from hole to hole on individualparts. I would expect repeatability to be very good on any properly set up machine, provided everything is tight with minimal backlash.

[ger21]

You might want to read throught the shopbot forums, and ask some questions there. http://www.talkshopbot.com/cgi-bin/discus/discus.cgi

[scrap-happens]

Our shop had a Shop-Bot and we cut 1000's of parts with it. When we did have a problem with it, support was great. We even cut lots of 3D items. You can't beat it for the money.

[Ravi]

Thanks Scrap-happens

What kind of problems you had with it?

Thanks

[scrap-happens]

Mostly user error, like accidentally unplugging a live stepper and frying the board. Occasionally you need to make sure the machine is still square and true. It is easy to do with a v-bit and scrap of plywood. Just manually mark a line in the x and y direction and check with a square.

One of the biggest challenges with the machine is coming up with a way to mount the part. We found it very efficient to make jigs that use wedges and pins to hold parts. That way all you have to do is tap on a few wedges to install or remove a part and if you make a mistake you don't ruin an expensive bit.

Another problem we had was the rack and pinions get clogged with sawdust and will make it jump time. You just have to keep an eye on it and blow it out occasionally.

Also, the boom that supports the wires is crap. Once we removed it and installed IGUS track it was much improved. Hope that helps.

[Ravi]

Thank Scrap-happens

[Joe Crumley]

Ravi,

I would encourage you to consider Ez-router.com. This is a much more stable CNC than Shopbot. It cost less also.

I've owned both and the EZ is far ahead.

J
www.normansignco.com