CNC gantry clearance: standard 6", or optional 10"

[iSign]

I was reading through the documents on the Multicam being built for me, and noticed a reference to the gantry clearance.
I asked my sales rep for more information on the notation of a standard 6", or an optional 10" clearance.

Someone on another board mentioned the limitations of insufficient gantry clearance on two different router threads I've posted, and mentioned doing a 10" thick job recently.

$2500 is a sizable chuck of change, but it's also a relatively small percentage of an upcharge on the whole package of this expansion I'm working on, so I'm inclined to go with the optional 10" gantry clearance.

Are there any other downsides besides cost, that anyone knows of, or other opinions in favor of this?

I talked to the sales rep, & he didn't feel that increased gantry clerance was typically needed in the sign industry.

He also pointed out some more possible drawbacks for me to consider, other than just the cost.

The additional height of the gantry, could translate to more "sway" between where the software is telling the bit to go, and where it ends up going, also risking more chatter or vibration affecting the quality of the cut. It seems there are slower RPM thresholds on a longer bit also, which could also effect quality.

Based on his opinions, it may not be a great idea, but I've also heard some very compelling opinions in support of that upgrade. I guess I'm leaning a little more toward the extra clearance now. One consideration in keeping all my options open, is that Maui is a small island, and this means having possibly the most versatile router on the island could bring me some good jobs outside of the sign industry...

 

[andy]

Doug,

Router bit length is the key to this question. Can you buy 10" router bits in the small sizes needed for sign work? Don't forget that the overall tool length isn't how deep it will cut- you need to allow enough length to grip in the collet.

You also need to factor in the lift and traverse factor- if you are cutting 4" material the gantry will have to lift the bit a total of around 8.5" from the bed to traverse your workspace.

Long router bits tend to break a lot- unless you are working with softer materials like HDU.

If I were specifying my router again I'd stick with a standard 6" gantry and spend the extra money on automatic tool change. ATC is an option which would add a shed load of efficiency- especially on 3D work.

 

[k.a.s.]

When I first got my Multi-Cam I thought that the gantry was awfull low and I would need to cut thicker things. But after 6 yrs of having the router I have never had a job that I could not cut b/c it was thicker than 6".

Remember if you have somthing thicker you can always make pieces and glue them together. I also would not want to have to use long bits all the time, I think the shorter the bit the better it cuts. And when your making signs you need 1/8" bits sometimes and I think you would have trouble with breaking a 4"or 5" 1/8" bit.

The only reason I wish I would have a little taller gantry is to rout flutes in 6x6 posts, but I usally just make somthing to attach to the posts that looks like flutes.

I think there are times when you may use it but overall I probadly would not spend the money JMO. Good Luck

Kevin

 

[3dsignco]

Doug, I Modified my table to get a 12" clearance.. In 15 years of CnC work. Needed it once. Had some 4" material. Save your money. If your ever going to need that thick cut and stack.

 

[iSign]

valuable advice guys... keep it coming.

I learn more each time I hear from the guys in the trenches... I somehow thought the collet could still travel down to a 2" block of foam, to use the same short bit... and I'd only need long bits for the rare thick cuts.

 

[k.a.s.]

I don't know how they make the router, but maybe the collet does have more travel so maybe you could still use regular bits. Even so I just don't think you would use it enough to justify it.

Kevin

 

[seattle]

Have you ever needed to cut something 10" thick on a router?

Me neither.

 

[GB2]

Bill's comment above reminds me that your Enroute software has the ability to slice through an object therefore allowing you the ability to rout in any thickness you chose and stacking the pieces for final assembly. I think I'd stick with the 6" unless I had a specific need otherwise, that is something that you'd have to deal with negatively for 98% of the time and only value it 2% of the time. It's not like going from a 4' x 8' table to a 5' x 10' table where there is very little negative impact but the extra capacity is there when you do need it.

 

[mgieske]

I'd assume the stability (chatter) issue exists only when cutting hardwoods & thick aluminum. If you're cutting alot of HDU & plastics, I wouldn't be concerned about loss of edge finish quality with the taller gantry. There's plenty of 5 axis machines out there cutting just fine with over 48" of Z clearance.

On the other side of the issue, we rarely cut materials thicker than 3" & have used the Z slice feature in Enroute when needed. It can be difficult to find the thicker materials.