Dowels Doable?

[woodturner]

Hello All,

I am looking for input on creating cab parts accurate enough for dowel construction. Has anybody done this successfully? We have made parts for staple and screw construction but they can be "tweaked" during assembly. We have checked squareness by measuring diagonals of a large cut and get excellent results (almost immeasurable), but get mediocre results cutting a door or drawer front. Sometimes lefts and rights of cabs don’t match. Thus far, we have had much better success cutting on the saw, then going to our “aged” point to point. Every year (about this time), I get re-energized about getting the “bot” into service for more than the occasional curved shelf.

By way of background info, we have a 5x10 Alpha, 2 spindles and air drill, and 15hp vac table. Everything appears tight and square (except the air drill which is why we are looking at dowels). Machine was set up by a machinist/toolmaker. Basically, it’s going to take MAJOR effort and time to attempt to get our over priced software to work with our frameless designs and put out useable data for dowel construction. Up to now, we do it all in A’ cad manually. I just want to know if it will ever be worth the effort. Can the machine deliver the goods? If so, we will be looking into investing in further process automation, such as the vac zones and hopefully, pop up pins (like the ptp) and so on. Any advice is tremendously appreciated.

[Gary Campbell]

Ed...
You dont say if your machine is a PRT or PRS Alpha. If it is a PRS, I say, without a doubt. If you have a PRT of that size, then I would say with the additions of the rigidity & cross bracing upgrades that are available, then yes to the PRT. Either way, you need to make sure that you have positional accuracy both under and without load on the tool. Cutting panels square requires under load accuracy, and drilling usually uses no load moves and then a drilling action.

You need to make sure that the machine is perfectly square to get the results you desire. If it does not stay that way, then there is a mechanical or physical reason. This could be as simple a bit flex or a smaller part moving, or as complicated as a combination of loose V rollers, flex of gantry members or unwelded joints moving slightly.

In the next couple weeks I am installing an air operated panel positioning system so that panels can be processed on the Bot, whether they were cut on the saw or Bot, before or after the edgebander. This should help us eliminate some production bottlenecks.

I am convinced that you have all the right pieces to do what you need to do. You may just need to tune one or more of the elements that you mention for optimum performance.
Gary

[woodturner]

Gary,

To be honest, I no longer remember if it's a PRT or not. It's mostly a storage table. It has no unistrut. It has the built up "Y" car with aluminum extrusions running under the blue angled rails. The spindles are mounted facing each other inside the steel car. It has the large aluminum control cabinet.

I see you're thinking like I am. Sort of converting the Bot to a PtP. I have been looking for the right components to do that as well. I wish I could nest the parts I need (mostly verticals only) and just go, but all the steps required to run (I think someone here dubbed it "like a space shuttle launch") has made it too cumbersome for either of my employees to tackle.

Maybe the simplicity of pulling up one of a dozen programs for zone A or B and hitting start can make it more palatable. I spend way too much time quadruple checking things and playing "clean up" guy. Slinging full (5x9) sheets around gets old too.

[Gary Campbell]

Ed...
Yes, from the description, it is a PRT alpha.

Yes, we are going in similar directions. I am looking to have the Bot do all the items that is will do better than any other machine first. Then, because it doesnt require supervision, task to it any operations that it can do equally.

Along with this I am working on the files that actually cut (not nest) and drill any rectangular cabinet panel without any drawing, just numerical input. This means that panels can go to the slider and/or the edgebander before the bot. You could easily add dowel drilling to vertically oriented panels to this type of file. It also means that we need a very good method of exactly locating parts on the table. The same applies to your doweling.

We are a small shop, so nesting and some of the production operations are not a priority for us at this time, however, our developement of specs for a new line of green cabinetry for both commercial and residential use are mostly complete. This new line, should it have our anticipated demand, may make those production operations necessary. Our ShopBot will be ready, but I am with you... tired of slingin' sheets.
Gary

[woodturner]

Yup, the exact location would make a world of difference. I like the pop up pins on the PtP. I have custom cut a "nest" after I screwed it to the table, but it's very inconvenient. Also, some automatic positioning of the head to get out of the way of removing parts, then moving elsewhere to load the next sheet (assuming we stay with nested sheets). Lastly, automatic dump of the vacuum and re-engage of the vacuum without turning off that power hogging pump.

None the less, I'll ask again if any one has successfully bored dowel holes (with the router bit and cut accurately to size with the same bit, repeatedly), please let me know. I suppose I need to slow down and speed up the spindle in the program. I know I've heard of others doing this. We are putting out commercial cabs and getting there quick is the key. Right now the old PtP is Ok but the day will come when I need the back up of the Bot (or other method). I am needing to hear if others are getting consistent results in the real world before I put another hundred hours in to getting the software packages to "play nice" together.

Thanks again to all!

[wooden_innovations]

I use my shopbot to cut my cabinet parts.

It cuts my stopped dados, shelf pin holes, pilot holes, pocket holes, back dados, and then cuts my parts out. I am using Autodesk Inventor to parametrically design my cabinets.

I recently considered dowel construction. The holes in the sides of the parts would be the easy part. I would trust my shop bot to drill as many dowel holes as I ever needed. The accuracy part that has me stumped is drilling the horizontal holes. I know that I could use the bot with a vertical fixture on the side, but some of my parts are over 3 feet long and I don't want to elevate the table of my shopbot to allow for longer panels.

Dowel construction would be easier and save some steps in the long run.

I am using a prt alpha with pc router, a drill mounted to a 2nd Z-axis, and two feins for vacuum.


Rodney

[rhfurniture]

Could you build a mount plate to rotate your drill 90 deg:
7184
That router is bolted on the back of my 1 Z, but I plan to build a rotating one on a second Z soon.

[sailfl]

Ralph

What do you cut with router in that position?

Thanks

[woodturner]

Rodney,

I would not even dream of trying to drill the horizontal holes on the Bot. I have horizontal heads in the PtP and they vary. I would drill horizontal on a dedicated construction drill. It seems that folks have thought about it, but aren't actually dowel drilling and cutting, and getting flush joints. I'd still like to hear from someone doing that.

Thanks!

[Gary Campbell]

Ed...
I am in the process of rebuilding our table to accomodate a second Z. When complete I will be adding a jig to the table that allows the horizontal drilling (in a vertical position)something like I have done for dovetailing drawers. Of course the table height limits the length of that panel being drilled, but the majority of our panels will fall within that limit.

We have done many mortise and tenons like this and there is no accuracy problems. Seriously, if you dont have that kind of accuracy in your machine, especially for drilling, then it needs a tune up or repairing.
Gary

[gene]

I am also thinking of going this route , but for the horizontal holes i am thinking of a dedicated horizontal boring machine or find a old used shopsmith . They were very good at this type of boring application , and its still cheaper then retooling the shop or new software.

[myxpykalix]

Gene there is a yahoo shopsmith user group, something like "SSusers". I recall guys always selling theirs on the group. The shopsmith is a tough piece of equipment so one even 25 yrs old would be in decent shape.

[rhfurniture]

Nils,
Mostly round-end-tenons, also holes and shaping for chair leg ends, including those little recesses for glueing leather patches in to make them glide nicely over the floor, etc etc.

R.