[Plan_B]

Hello!
I would love to hear from anyone who is using their machines for regular nested cabinet work or similar. I'm a Mechanical Engineer and I work in marine and factory automation. One of my side projects/hobbies is making toys and I built a 6' by 12' router last year for this. It's been working for about 20 hrs per week for about a year without any major hiccups.

So when my friend asked me if I could help automate his countertop/cabinet business with CNC capability I jumped on it. I'm going to build him a 6' by 16' machine that he can use for his wood/corian/etc countertops and to take in-house and external nested cabinet jobs and some sign work. - at least, thats the current idea.

I think on a machine like this one, vacuum hold down is probably unrealistic. I imagine it would need at least 30 or 40 Hp vac pump. On my machine, I use screws/tabs and it works great for what I do (its a combo of large and very small cutouts) - there's no vacuum hold down.

I want to reassure my friend that tabs are a viable option, even for production cabinets as I am convinced of this. But tyhen again, I've only done small cabinet jobs on my machine. It worked great (I think), but I want your opinions before I move ahead. Is anyone here volume-producing nested cabinet cut outs without vacuum hold down?

Thanks for reading such a long pre-amble. I appreciate your time and thoughts!
I hope to hear from many of you..

[ger21]

I do production cabinets, using vacuum, and I can't imagine using tabs, as it would probably take 3 times longer.

I have a couple questions.

Why do you need a 16' router?
We have a 5x12 machine, but 99% of what we do is 4x8 sheets. Yes, we have two 25HP vacuum pumps, but most of that is just sucking air through the 5x12 spoilboard.
What I'd recommend, is to have the vacuum confined to a 4x8 area, or whatever the most commonly used sheet size is. You don't need a huge pump for a 4x8 area. See what the Shopbot guys are doing with these motors. ShopBot Vacuum Motors

I could use a smaller spoilboard to concentrate the vacuum, but since we have the pumps, using a 5x12 spoilboard save a lot of time switching between different sized spoilboards.

What volume do you consider "production"? We can cut about 10 sheets/hour with vacuum, and probably couldn't do more than 4 using tabs.

[Plan_B]

Hi Gerry,
Thanks a lot for putting in..
The arguement for a 16' machine is as follows..
1. countertop millwork, certainly not always, but often entails slabs over 12' long. If we decide to make the machine large enough to account for that, then I was thinking its logical to make it 16' rather than arbitrarily say 14', or 15' so that the table size is in accordance with plywood sizing.

2. On my 6' by 12' machine, I normally run 5' by 5' sheets, but I use toolpaths to cut 2 sheets at a time. So every run cuts 5 x 10 worth of parts between sheet changes. It's a huge time saver (I think). I thought for the cabinet shop application, we might be able to leverage off of the same concept - cutting 2 4x8's per tool path.

3. I'm also moving my 'toy' production into his shop, with plans for another machine when needed. I thought that since he thinks 12' isn't long enough to cover 'all' of his mill work then I should make it long enough to take 3 5 x 5's per run (or 2 4x8's).

The shop this all happenning in is about 10000 sq.ft. so space isn't a premium

4 sheets per hour doesn't sound all that bad, but then again, I'm not in that business.. what, if you don't mind my asking, would be a reasonable $ turnaround on that rate? Does the idea of cutting multiple sheets to save time make sense to you? Once the pockets are cut and you move on to profiles, the profiles are cut one sheet at a time, so you can change sheets while the profiles are being cut on subsequent sheets. Once the run is done, you just change the last sheet and start over... That's how I do it with the toys I make - 2 sheets at a time.

So I think I need to think about whether multiple sheets per run 'actually' adds value... But hypothetically speaking, if we keep to the large size and then no vacuum, how do you find that 'tabs' perform? You would have to use an edge router to remove the tab reminants. I cant see this as problematic - other than the time it takes... but then again, I've not done this on several sheets per hour. You would have to avoid fouling the edges when doing this. Do you think the results would be reliable at least?

[Plan_B]

Hi again Gerry,
I checked out the vacuum pumps on that link, and some of the threads on the shopbot forum. It looks like those pumps are max ~650W, which is just shy of 1 Hp if I'm interpretting the specs right. Am I correct then in assuming I'd need a handful of them to hold down a 4x8 area?
Man... I wish I had the budget to swing a couple of 25 Hp vac pumps! But that would be about 10 times the cost for the machine..

Is it okay if I add another question to this thread? How about spindles? My machine uses a Porter Cable 3 1/4 HP router. It's fine for what I do but I'm pretty sure we'll need more oomph than that for cabinet work if we want to be productive.. I'm figuring about 3-5 HP. I'm budgeting for that with VFD about $3K-5K. Anyone have any advice/suggestions?

[ssutton]

I run a 4' x 4' machine with 1 of the shopbot type vacuum pumps zoned into 2 2x4 areas. It works great for FLAT stock plywood with absolutely no bows or curls. In reality, it just does not work for materials that you go get from lowes or home depot, BUT, I made my machine to cut aluminum and plastic sheets and it does work super for that application. I never have to worry about material movement during machining even with high cutting forces. It just does not deliver the volume/suction that a commercial pump can but with specific materials it can work great.

[ger21]

In reality, it just does not work for materials that you go get from lowes or home depot

Our two 25HP pumps won't hold don't warped material either. Regardless of your vacuum pump, the material MUST be flat.

For best performance with those vacuum motors, Shopbot guys use 4 of them on a 4x8 table.

The arguement for a 16' machine is as follows..
1. countertop millwork, certainly not always, but often entails slabs over 12' long. If we decide to make the machine large enough to account for that, then I was thinking its logical to make it 16' rather than arbitrarily say 14', or 15' so that the table size is in accordance with plywood sizing.

How is he making his countertops now? We rarely cut countertops on our router, unless they are curved.

2. On my 6' by 12' machine, I normally run 5' by 5' sheets, but I use toolpaths to cut 2 sheets at a time. So every run cuts 5 x 10 worth of parts between sheet changes. It's a huge time saver (I think). I thought for the cabinet shop application, we might be able to leverage off of the same concept - cutting 2 4x8's per tool path.

OK, that might save a little time.

It really depends on the volume you're trying to do, and what your costs are. 4 sheets/hour is way too slow for our needs.

I've actually never used tabs in the 15 years I've been doing this. In a high production environment, it's just not an option.

You would have to use an edge router to remove the tab reminants. I cant see this as problematic

I do how do you flip a sheet full of parts with only small tabs holding them together? If I couldn't use vacuum, I'd use onion skinning before tabs.


As far as a spindle, that depends on how fast you want to cut, and how much you're going to use it. You can get Chinese 3HP (2.2Kw) water cooled spindles with VFD for around $400. For a table that large, I'd probably go with something a little larger. Chinese spindles from Ebay are very inexpensive, and are used by a lot of members here. But you have to consider them disposable. Ekstrom Carlson are supposed to be pretty good, as are Colombo, and HSD.

[Plan_B]

And, for most cabinet work, I imagine the material is almost always pretty flat.. Melamine, MDF, even 1/2" baltic birch is usually pretty flat. I'm going to start thinking about vacuum for this. So 4 of those pumps on a 4x8... Well, the price for them is right for that... Do they just use one inlet on the table per pump, and a matrix of grooves under the spoil board?

I haven't yet been to his current countertop shop, but he says they use "hand tools" now. He intends to bring in a supply of a composite "paper-based" product that looks alot like stone or Corian. the OEM recommends cutting with a router. This is the driver for the CNC router requirement for him.

On the 'toys' stuff that I do, I only need to use tabs for small parts because they shift a lot at the ends of the profiles, and get sucked up through the dust vac!, otherwise, I just screw down the edges of the sheet and cut - no vac, and no tabs for parts bigger than ~8-10".

But when I DO use tabs, removal is pretty easy.. Use a Fien ultrasonic blade to cut the tabs, then a flush-trim edger to clean the tab off. I have a hard time with "skinning" because of the outer veneer grain on the birch plywood - it makes a mess!

What do you think about a 4 HP ekstrom Carlson spindle? enough power? or should I go up to the 6 HP? I'm not sure what the price difference is between the 4 and the 6, but the 4 HP is only $2500 with VFD and all accessories - Not bad considering it has a waranty and a manufacturer you can talk to...

[Plan_B]

Well, Thanks alot, Gerry and ssutton for your advice so far. I appreciate it. I think I'll start another build log for this when it gets closer to build time...

[wcarrothers1]

I have 3 ekstrom carlson spindles (2 c73's and a 78) and they have been trouble free. First one I got back in 2006 and has been running on my first machine since then. Their service is great as is their response to questions.

On all of mine I opted to get my VFD from automation direct though. And for the larger one I have a seamans brand VFD (seeing automation didn't make a single phase 4 hp one at the time and still dont.

Personally I think they are worth the extra cost vs going china cheep. Biggest turn off for the china spindles least for me is they all seem to use smaller ER20 or smaller collets. And I'm already using ER25's on my ekstrom's.

Also they are uniform shape so all my skirts and stuff fit. And on the 1 machine I have them mounted side by side on independant Z's so having the same dim's was important so they would both align.

b.

[Plan_B]

Thats great info on the spindles - Thanks a lot. Ekstrom Carlson has been helpful to me so far. It's nice to know they will be helpful after I buy from them. lol.

I'm deciding between the C78 and C93. The specs say they are 3 phase. Do you know, schematically, how these spindles work? Is the VFD actually providing the 3 ph power source to the spindle, controlling the spindle speed by varying the frequency? This was my understanding but I'm not sure. Will I need to bring 3 ph power to the machine? or does the VFD convert the normal 1 ph 220 into a 3 ph signal?

[Plan_B]

With regards to the shop bot vacuum hold down - I'm looking at the "plenum" design on the shop bot website. As Gerry mentioned they use 4 ~ 1 Hp vacuum pumps to provide suction in 4 seperate zones on a 4x8 table.

The only pictures I can see on their site of this plenum, look like each zone has an outlet for the vac piping in the middle, and there are groves/channels emmenating from the outlet in an 'X' shape, ending in a groove around the circumfrence of the zone. So from the picture, it looks like the vacuum is only applied to the spoil board where the grooves are. It seems to me you would want a lot more of those grooves to distribute the vacuum more continuously on the whole area of the spoil board.

Can anyone comment on how those grooves/channels should be configured?

[ger21]

It depends on the horsepower of the spindle. For 3HP and smaller, you can get a VFD that accepts single phase and provides the 3 phase to the spindle. There's a limit to the maximum HP spindle you can run from single phase, and the VFD's are harder to find. Ekstrom Carlson should be able to tell you how large you can go on single phase, and they should be able to supply a VFD.

[Plan_B]

Well..
It's been a couple of days and we haven't had one person come out and say "yes, I make cabinets without vacuum", So I guess it's safe to say that the concensus is that Vacuum is a must? Or am I speaking too soon? Anyone?

I was holding out for another answer lol! but the upside is that I think I've found a way to get vac on the machine without necessarily spending 10-20K on pumps! So most likely this build will includes vacuum hold-down... Thanks for all your input! This forum rocks...

Once I start the detailed design/build I'll put up a project log.

BTW, Gerry, I've been using your screensets for several months now and I cant (and dont want to) remember what it was like without them. The homing, tool change, z zero-ing, and other features are huge time (and effort) savers!

[ger21]

It's been a couple of days and we haven't had one person come out and say "yes, I make cabinets without vacuum", So I guess it's safe to say that the concensus is that Vacuum is a must? Or am I speaking too soon? Anyone?

There just aren't that many people here building cabinets. You might get a better response at Woodweb, but it may not be any different.

[Falcon69]

I build cabinets and have used a CNC with a nested base vaccuum system, and a pod base vaccuum system. As well as a cnc without a vaccuum.

Nested base hands down is easiest. Allthough, the Weeke machine I used that had pods was also kinda nice, because I could drill the sides for dowels. But, on the downside, if you aren't careful and watch where you place the pods, you'll do one of two things, both bad, one really bad. 1. You'll route into the pod, destroying it, and 2. the spindles and line bores will come down and hit that put and keep going, bending the linebores and spindle. very costly. I did that by accident, wasn't paying attention. cost a bundle to fix.

I plan on building mine with nested base and using a spoil board. It makes life so much easier. The only time when a clamping system is nice is when you're milling solid wood. Guitars, carvings, etc. That's why I'm making my machine so it can have clamps or vaccuum. I'b building aluminum channels in between the zones, and I'll have 32 zones, as the channels are 12" on center.