Start of a New Design

[ger21]

Although I still haven't finished the router I started 4 years ago (soon, though), I've picked up a lot of information over that time. And with that information, my ideas for the next machine have been constantly changing. But I think I now have a pretty good idea of what I want, so the design has begun. It'll be mostly wood (no MDF); Baltic Birch ply and epoxied laminations. Everything sealed in a few coats of epoxy to minimize wood movement. The current plan is to use V-Rollers for the X and Y axis.

Some of the guys building Joes machine are using an ATC. For years, everyones wanted an affordable ATC, and now that ones available, I'm going to go in a different direction. Two spindles. The ATC with a bunch of tool holders is not exactly cheap, and it's got that 10K rpm limit. It also adds a bit of length to the spindle, possible increasing runout. I figure that two tools will cover most parts without a tool change, and it's a little faster than an ATC. In the end, it may cost a little more, but not too much. It also gives me the option of using a drill for the second spindle, which will let me easily line bore cabinet sides.

My first router uses round shafts and bearings, which work good and are fairly easy to build around. But with 2 spindles, I need to try and get everything as compact as possible. We recently had to pull the 10HP spindles at work to have them rebuilt, and I saw that they are mounted with 2 blocks on a single 25mm rail. They do use roller bearings, but the things weigh about 40 lbs, and can cut about 500 ipm at 1-1/4" depth of cut. So I figured that they would be good for a 2-1/4HP router. I decided on HiWin 20mm with flanged blocks. I started with 18" rails, but just changed to 15-3/4" rails (400mm). I can still pull a 4" router bit above the bottom of the rails, and can get about 8+" of travel. Right now the total width of the two spindle holders is about 12", not too bad. The spindles are 6-1/2" OC, so a 60" wide gantry should give both spindles access to a 48" panel. That's the target width right now. The tricky part is trying to squeeze two leadscrews in between the routers. I'll be using 1/2" acme and dumpster nuts. The screws will be belt driven.

Anyway, here's a few preliminary pics.

[Greolt]

I'll be keeping an eye on this as your ideas progress Gerry. See what nice ideas you come up with.

The two spindle concept has plenty of merit IMO.

I don't believe running one rail per spindle will be a problem if done right.

I see by your pics that the spindle center line can go even closer to the rail which would be desirable. The closer the better.

I do however think you will need to mount the rails on something better than wood.

They only have a 20mm wide mounting surface. An aluminium (Aussie spelling ) plate would fit the bill nicely there.

Greg

[Oldmanandhistoy]

Hi Gerry,

I’ve been looking forward to this thread for a long time now so will be following very closely.

Anyway your first post and I have questions already.

I have considered the two spindle idea on a couple of occasions but instead of the dealing with the complications have gone with a quick change spindle setup. Basically I just switch spindles which are set up with various cutters; not ATC but close enough for now. Possible because the Kress spindles I use have a plug in power cable.

I’m sure you must have considered and rejected it but what do you think of mounting two spindles back to back (either side of the gantry)? Thinking about it, it would mean a longer X axis which would increase the likelihood of screw whip if you are going with screws and not R&P?

How confident are you about being able to mount the single Z axis rail rigidly enough to plywood? My first thought after looking at your picture was, is it possible to have a third rail floating between the two Z’s but that idea seemed to complicated and possibly would not help if it would work at all (needs more thought).

John

[ger21]

I see by your pics that the spindle center line can go even closer to the rail which would be desirable. The closer the better.

I think it's only 1/4" off center. I don't think that will make much difference, but I may be able to move them back to center before I'm finished.

I do however think you will need to mount the rails on something better than wood.

They only have a 20mm wide mounting surface. An aluminium (Aussie spelling ) plate would fit the bill nicely there.

Greg

I originally started with a piece of 3/4" aluminum (correct spelling )tooling plate. However, it would run about $100 for the plate, and at least that much more to have it machined. So I came up with a different plan. I'm going to machine a rabbet in each edge of my panel, and fill it with thickened epoxy. Once the epoxy cures, It'll be re-machined to provide a hard mounting surface with an alignment ledge. The panel will be part of a box, which will be filled with an epoxy-sand mixture, and will have steel angle epoxied in as well for reinforcement. Inserts for the V-rollers on the back side will also be epoxied in. I'll mount the rails, using t nuts or some type of insert nut prior to filling it with the epoxy mixture.

So I'll actually be mounting to a hard epoxy surface, with the nuts anchored in the epoxy mixture.

[ger21]

I’m sure you must have considered and rejected it but what do you think of mounting two spindles back to back (either side of the gantry)? Thinking about it, it would mean a longer X axis which would increase the likelihood of screw whip if you are going with screws and not R&P?

Side by side provides much easier access when changing tools, I never considered the back to back method. It will be screw driven, but not 1/2" D, and probably 1-2 turns/inch. This will be a very fast machine.

How confident are you about being able to mount the single Z axis rail rigidly enough to plywood?

John

Very confident, see previous post. Also, I may laminate the plywood panel myself, in a vacuum press, using 1/16" maple veneer with epoxy, maybe 1" thick.

[neilw20]

Ever thought of using a single screw between the spindles with an arrangement where the heads are either parked at the top, or latched onto the nut of the screw, which could rotate from one side or the other to pickup he head.
Is this only one step away from a carrosel? (can't spell. I no it)

[Oldmanandhistoy]

So I came up with a different plan. I'm going to machine a rabbet in each edge of my panel, and fill it with thickened epoxy. Once the epoxy cures, It'll be re-machined to provide a hard mounting surface with an alignment ledge. The panel will be part of a box, which will be filled with an epoxy-sand mixture, and will have steel angle epoxied in as well for reinforcement. Inserts for the V-rollers on the back side will also be epoxied in. I'll mount the rails, using t nuts or some type of insert nut prior to filling it with the epoxy mixture.

So I'll actually be mounting to a hard epoxy surface, with the nuts anchored in the epoxy mixture.

I very much like the idea of using steel to reinforce the plywood structure and have considered using steel flat bar, in grooves and fixed with epoxy (so in bedded in the plywood). The only problem if indeed it is, would be the different expansion rates of the two materials; do you think there would be a problem or is it over exaggerated IYO?

Have you considered routing a rebate for flat steel bar (instead of your epoxy) to fix your Z rails to?

John

[ger21]

Ever thought of using a single screw between the spindles with an arrangement where the heads are either parked at the top, or latched onto the nut of the screw, which could rotate from one side or the other to pickup he head.
Is this only one step away from a carrosel? (can't spell. I no it)

No, but our router at work uses a single screw, and each spindle is raised or lowered independently using pneumatic cylinders.
But I think i could move them quicker if they are seperate, due to the much lower inertia.

[ger21]

The only problem if indeed it is, would be the different expansion rates of the two materials; do you think there would be a problem or is it over exaggerated IYO?

Over exaggerated. My garage is heated, so the temperature variations won't be that great.

Have you considered routing a rebate for flat steel bar (instead of your epoxy) to fix your Z rails to?

John

To much trouble to drill and tap the holes. Theres only about 0.5mm of room around the mounting bolts, so if one hole is off just a little, it'll make alignment difficult. Keep in mind that I'm building this with woodworking tools. I'm taking what I think is the easy route. I can shim the mounting bolts so they are centered in the rail holes, then when I bond the nuts in place, they should be in perfect alignment.

[eigstein]

hi, gerry i am a retired boilermaker and don't type well. look at your plan dwg. its not the spacing of the rails that cause a deduct from the y axis its the dia. of the spindles plus the size of the carriers. this doesn't change . two rails or four rails. cost wise you may be able to use lighter and less expensive rails. i always read your posts. keep up the good work. sincerly , eigstein

[BobF]

Gerry,
All of your ideas look well thought out. At this point I can't find an area I would argue.
Keep up the good work.

[Greolt]

I think it's only 1/4" off center. I don't think that will make much difference, but I may be able to move them back to center before I'm finished.

What I meant was in the direction shown with the arrows. The closer the better.

............and fill it with thickened epoxy. Once the epoxy cures, It'll be re-machined to provide a hard mounting surface with an alignment ledge. The panel will be part of a box, which will be filled with an epoxy-sand mixture, and will have steel angle epoxied in as well for reinforcement. Inserts for the V-rollers on the back side will also be epoxied in. I'll mount the rails, using t nuts or some type of insert nut prior to filling it with the epoxy mixture.

So I'll actually be mounting to a hard epoxy surface, with the nuts anchored in the epoxy mixture.

Wow when you start talking about epoxy sand mixtures etc I'm lost. I'm a metal sort of bloke. Aluminium plate is just the way I naturally think.

To me it is just makes more sense. The rails are metal. Anyhow each to his own hey.

Greg