Help choosing small CNC router

[PEZSEZ]

Hello all

Looks like I am yet another newbie-- but that's how forums grow right

My company specializes making audio products for the power sports industry-and were best known for doing things with Harley Davidson's. We recently built 24" x 48" vacuum thermoform table with a goal of mine to have a CNC router on-site. Apart from doing signs etc. for our dealers, we want to be able to draw things in CAD, have to CNC carve the design out of foam blocks, and then use the foam block as a mold on the thermoform machine.

This would be a nonproduction application where speed does not matter too much. I have been looking at machines such as the AXYZ millennium which is 3' x 3', and the Shop Saber at the similar size. We have even looked at the carvewright but that one makes me nervous........

We want to be able to cut plastics, wood, foam, and sometimes aluminum. I welcome anybodys input on which way we should look-I would like to keep the price at around 12,000 Canadian or less.

Any input is greatly appreciated!--PEZ www.hogtunes.com

[LimitLess]

I have been reading the threads about different CNC Routers and, like many other products, it seems to depend on an individual's. I have not purchased a CNC yet, but production is calling for it. I need some advice.

An opportunity has come up from a small engraving company that has a 4x8 Warthog about 10 years old(?) with a Porter Cable 3.5 hp router on it. The Router was replaced 3 years ago. The software was upgraded 2 years ago. I don't know enough yet to specifiy servo or other technical data. I have outsourced to them and it is clear that there strengths are in smaller engraving equipment. They are asking 7600.00 for the set up. They are willing to move it to my shop.

For my Company, I am not proned to purchasing used equipment. But I have seen this machine function and I have not seen any problems other than operator issues.

I have spoken with an experienced rep and he is willing to inspect it but he is not an operator.

What can I look for and what do I need ask? Any suggestions? If I do not purchase the Warthog, it is certainly available to anyone else interested and I would be glad to set up the contact.

[woodman08]

have them cut some squares on a 1/4 panel and circles ,see if the cuts line up also check the diagonals of the squares ,then run a bit down the table see if the height stays,check the bearings for play ,check the drives see how hot they are running after say 2 hours .
Check to see if it will return to zero ,the spot you set as zero ,run it to the end of the table ,hit return to zero.
Have them re-surface scrap piece on top the table ,what how it works

[LimitLess]

Thanks Woodman
It' s funny. I was so concerned about the technical aspects that lay behind the machine that it had not occurred to me to check the tool for its basic functions. I appreciate the re-alignment.
As I was reading your suggestions, these little quirks that I had been experiencing from the output of the jobs began to appear as machine-related, at least to the 50/50 mark, and not just operated-related as I had assumed. There does exist, however, the lack of carpentry and woodworking skills in the staff. Such as stops or jigs, the practice of stacking parts, or establishing a constant "zero" within a series (I have seen this and it made no sense to me.) As in the arch/eng community, many techs are trained in the software only and have no real connection to the material or processes related to each. For now, this my advantage.

Can I feel confident that any of these tests that you suggested would expose problems that are predomniantly calibration issues, apart from worn bearings prehaps?

[woodman08]

I think when you run basic shape tests it will indicate somthing is out ,warped and maybe wear.
After running the square,depth ,zero return and if its ok then its ok ,if not then the table could be warped from possibly moving it or iof the trable is square and the gantry is running ok then look for wear.
steppers and electronics are very reasonable to replace and re-wire i have done it but the table and the bearings thats an extreme acurate setup

[LimitLess]

Today's assembly testing had some indications of vibration. The project consists of a perforated MDF panel 73" x 37". The holes are to receive a 1/4" 6061 aluminum rod. These rods measure more accurately at .258.
A .25" spiral-cut bit was used to drill the holes straight down. I'm sure the router doesn't even feel the MDF.

The .008" makes a difference when trying to install the rods into the holes but I chose to have them tool the holes with a .25" to examine the consistency.

The results coming from this Warthog is a field of perforations in the MDF that range from .25" to something over .262". This appears to me to be a vibration but I have no real experience with operating or maintaining yet. Thinking about the causes produces a list including the router mounting, the router itself, perhaps the gantry, a possible warp, as you pointed out, and even the possibility of how the whole table is mounted (or not mounted ) to the floor, and finally bearings and guides. ?

Back to my thoughts of purchasing this Warthog. I think it best to see if I can get a Warthog(?) Rep Tech or someone experienced with these machines to look at it. I think the price ($7600.00) can still be good even if I had to give the unit a overall tune-up. I will take my time and chance that someone else buys it before I hastily embrace a can of worms.

[woodman08]

i do not think a end mill .25 spiral what ever is fair for drill holes ,it might vibrate naturally in mdf .
When i drill holes in aproject i use drill bit for drill holes ,now if you were pocketting then a flat end mill is the answer.
try the same drill hole with a drill bit

[LimitLess]

Okay. I need to stop applying non-cnc logic to this problem.
So if I need a .258 hole, which is .008" larger than a 1/4" shank, how would that be done on the cnc router? Or when I need the "E" diameter , which is smaller than a 1/4" shank?

If we use a "G" bit on a drill press, the chuck adjusts to the size of the bit. Does this imply that the router can accept something other than a 1/4" shank somehow?

What we have done is used a 1/4" bit and had the router path set up to mill the .258" diameter. Seems so straight forward. Should we employ a straight bit over a spiral?

I have sent RFQ's to have custom bits made for the router so we can achieve the dimensions via punch rather than diameter milling.

BTW - I really appreciate your time and experience. This has been enlightening.

[rowbare]

Originally Posted by LimitLess So if I need a .258 hole, which is .008" larger than a 1/4" shank, how would that be done on the cnc router?

Via circular interpolation. Assume a hole at position x0 y0 using a 1/4" bit, the following gcode will make a .1" deep hole .258" in diameter. Your cam program will figure this out for you

g0 x0y0
g1 z -.1
g1 x-.129
g3 x-.129 j0 i.129

Originally Posted by LimitLess Or when I need the "E" diameter , which is smaller than a 1/4" shank?

While many homebuilt cnc routers and lower end commercial cnc routers use ordinary routers, most commercial routers use router spindles that use ER Collets (if they aren't setup for automatic tool changers that is). These are industry standard collets that come in sets so one isn't limited to standard shank sizes.

While these spindles are quite a bit more expensive than the hand-held router, they are also built for continuous use. They have better bearings and tend to be quieter as well. In addition, their horsepower ratings are usually specified by the engineering department rather than the marketing department so a 1.5 hp is probably more powerful than the typical "3" hp router.

Router spindles vary widely in specs and prices, you can spend upwards of 10K on some but you can get decent ones starting at less than $1k. Also a lot of people here have been buying Chinese high speed spindles on eBay and have been having a lot of luck with them.

Here are links to a couple of spindles on eBay:

This is a 1.5 HP Columbo Spindle
http://cgi.ebay.com/NEW-1-5HP-COLOMB...ht_1044wt_1002

This is one of the Chinese spindles
:http://cgi.ebay.com/WATER-COOLE-MOTO...t_12082wt_1165

Here is a nice enough little router that might meet your needs:
http://www.kelinginc.net/CNCmachines6090.html
or a little larger:
http://www.kelinginc.net/CNCmachines1212.html

bob