L3viathan's Steel Router

[l3viathan]

Working out material for the table, and a single piece of 30" x 30" aluminum of reasonable thickness is not cheap. Since I have a couple large pieces .375" aluminum plate, I was thinking about laminating them (bolted together in various places across the surface) for a .75" table. I have to wonder if there would be vibration between the plates, since they are not precision surfaces? I'm not sure how few bolts I could get away with to hold the plates securely together in this scenario. I haven't run any calculations on it yet, but I imagine with the span I have, a .75" table shouldn't deflect very much.

Would it be wise to put a thin dampening layer between the plates? Maybe a thin sheet of HDPE?

[ger21]

I would epoxy them together. Bonding them is the only way to get them to act like a single panel. You still want a lot of screws holding them together to prevent delamination.

[gfacer]

Sand first, then immediately epoxy....sanding to take of the oxidization that rapidly occurs with aluminum.

Sent from my ASUS_Z00TD using Tapatalk

[ger21]

Even better is to "wet sand" the epoxy into the surface, with 80 grit sandpaper.

[wizard]

Working out material for the table, and a single piece of 30" x 30" aluminum of reasonable thickness is not cheap. Since I have a couple large pieces .375" aluminum plate, I was thinking about laminating them (bolted together in various places across the surface) for a .75" table. I have to wonder if there would be vibration between the plates, since they are not precision surfaces? I'm not sure how few bolts I could get away with to hold the plates securely together in this scenario. I haven't run any calculations on it yet, but I imagine with the span I have, a .75" table shouldn't deflect very much.

Would it be wise to put a thin dampening layer between the plates? Maybe a thin sheet of HDPE?

The first thought that comes to mind is to sell the plates and buy thicker one. Yes I know aluminum plate is expensive you could always buy a steel plate.

Considering the possibility that you don't want to spend the money i would suggest lots of flat head screws. To work well though they need to be installed with some precision. I'd look at 4-6" centers all around the plate. That probably sounds like a lot of flat head bolts, but you want the plates to act as one mass.

There are suggestions above about using Epoxy, that might be a good supplement to a bolted up solution but I wouldn't forget about the bolts. I'd be concerned about getting the epoxy to flow evenly to a consistent thickness, you would want to bolt up from the center outwards. You might also consider supplementing the bolts with an aerobic adhesive much as one of the Loctite bearing retaining compounds. I would have more confidence in the Loctite flowing well and not distorting the plates.

[l3viathan]

...you could always buy a steel plate.

I'm defiantly exploring all of my options, and not tied to using aluminum. The price is still pretty high with steel plate that large. I ran a bunch of FEA this morning using A36 steel plate of varying thickness, and was seeing about .0006" deflection with an 80lbf Ø12" cylindrical load in the center of .5" plate. That isn't exactly a scenario I would find myself in, but I thought it represented a good worst-case. The one drawback to using steel is that I was planning to surface the table using the machine itself, and i'm not so sure the 2.2kw chinese spindle would fare well in that, and my manual mill only has about 22" of X travel. I finally got a quote for milling the mounting surfaces on the base of the machine, and at $750 for ~300 sq in., I'd like to limit my use of their services as much as possible. I though grinding might be cheaper, but I can't even get the time of day from any place I've called.

I'm not adverse to layering plates, as my initial though was a steel plate with aluminum top, although I discounted that due to the likelihood of corrosion between the plates causing issues down the road. I do have a piece of .5" stainless plate, but it's more like 2' x 2'. I'm not sure I like that much overhang of a top plate.

I've also considered building a frame out of 40mm aluminum extrusion (I have plenty), and then putting a .375 aluminum plate on top of that, however it makes mounting a bit more difficult.

[louieatienza]

I'm defiantly exploring all of my options, and not tied to using aluminum. The price is still pretty high with steel plate that large. I ran a bunch of FEA this morning using A36 steel plate of varying thickness, and was seeing about .0006" deflection with an 80lbf Ø12" cylindrical load in the center of .5" plate. That isn't exactly a scenario I would find myself in, but I thought it represented a good worst-case. The one drawback to using steel is that I was planning to surface the table using the machine itself, and i'm not so sure the 2.2kw chinese spindle would fare well in that, and my manual mill only has about 22" of X travel. I finally got a quote for milling the mounting surfaces on the base of the machine, and at $750 for ~300 sq in., I'd like to limit my use of their services as much as possible. I though grinding might be cheaper, but I can't even get the time of day from any place I've called.

I'm not adverse to layering plates, as my initial though was a steel plate with aluminum top, although I discounted that due to the likelihood of corrosion between the plates causing issues down the road. I do have a piece of .5" stainless plate, but it's more like 2' x 2'. I'm not sure I like that much overhang of a top plate.

I've also considered building a frame out of 40mm aluminum extrusion (I have plenty), and then putting a .375 aluminum plate on top of that, however it makes mounting a bit more difficult.

You can buy phenolic sheet. They sell PaperStone remnants and blemishEd sheets at a discount. Many commercial machines use it.

[l3viathan]

You can buy phenolic sheet. They sell PaperStone remnants and blemishEd sheets at a discount. Many commercial machines use it.

I'm not familiar at all with the properties of phenolic sheets. Would you recommending them as a bottom or top layer in a composite with aluminum/steel, or wholly as the table itself? I did look at HDPE and UHMW, as I have some pieces (not large enough for a table though), however pieces large enough for the table I want are priced high enough to make aluminum plate preferable.

[l3viathan]

I picked up a .5" stainless plate that is 28.5" x 29" to use as a base for the table. I think it's 316, but can't guarantee that. As much as I like the specs of paperstone, I'll probably stick with an aluminum plate on top of that. I should have all of the steel in a week or two, and then this will be a real build thread.

[wizard]

It is now construction season, you could always hook a chain to one of those big plates, that all all over the roads and drag it home! 😱😱😱😵😵😕😕. Sorry was thinking about my drive into work every morning for the last couple of weeks.

I'm defiantly exploring all of my options, and not tied to using aluminum. The price is still pretty high with steel plate that large. I ran a bunch of FEA this morning using A36 steel plate of varying thickness, and was seeing about .0006" deflection with an 80lbf Ø12" cylindrical load in the center of .5" plate. That isn't exactly a scenario I would find myself in, but I thought it represented a good worst-case. The one drawback to using steel is that I was planning to surface the table using the machine itself, and i'm not so sure the 2.2kw chinese spindle would fare well in that, and my manual mill only has about 22" of X travel. I finally got a quote for milling the mounting surfaces on the base of the machine, and at $750 for ~300 sq in., I'd like to limit my use of their services as much as possible. I though grinding might be cheaper, but I can't even get the time of day from any place I've called.

I'm not adverse to layering plates, as my initial though was a steel plate with aluminum top, although I discounted that due to the likelihood of corrosion between the plates causing issues down the road. I do have a piece of .5" stainless plate, but it's more like 2' x 2'. I'm not sure I like that much overhang of a top plate.

I would be more concerned about war page from differential growth as temperature changes. For that reason I would not try to laminate plates this big made of dos iliac materials.

I've also considered building a frame out of 40mm aluminum extrusion (I have plenty), and then putting a .375 aluminum plate on top of that, however it makes mounting a bit more difficult.

It may be a bit more difficult to mount but may make for a stiffer table that is still manageable weight wise. Short of casting your own table you have no good way to control weight while keeping the table stiff. You may be able to weld up a table with a good set of ribs to make a stiff table but that is a lot of work. Either way a casting or weldment is fairly expensive to do one off so you are back to thick sheet goods. You could alway go extra thick and then cut lightening pockets in the rear of the plate.

You may notice I leaning away from trying to laminate anything here. This is due to the lack of a warm fuzzy feeling as opposed to anything concrete, experience wise. There maybe perfectly valid reasons to laminate like this but I've never seen it done in commercial work.

[l3viathan]

It is now construction season, you could always hook a chain to one of those big plates, that all all over the roads and drag it home! ��������������. Sorry was thinking about my drive into work every morning for the last couple of weeks.

The problem with that is, even if I managed to get it home, I'd have no way to mill the face of it flat

I hadn't considered thermal expansion differences though, so that is a good point. I stopped by a scrap yard today, and although they didn't have any aluminum plate in the size and thickness I wanted, I did get a line on a place that should have what I need. I was told they have thick industrial cast plate at scrap prices and even have the facilities to cast their own. The place is 2 hours away, so i'll give them a ring tomorrow, and make a trip this weekend if it looks promising.

If all else fails, I might end up just using the stainless plate as the table. It is very flat, so I might get away with using it as-is.

[wizard]

The problem with that is, even if I managed to get it home, I'd have no way to mill the face of it flat

I couldn't resist, these road plates are just about impossible to miss around here. What can I say I needed the humor.

I hadn't considered thermal expansion differences though, so that is a good point. I stopped by a scrap yard today, and although they didn't have any aluminum plate in the size and thickness I wanted, I did get a line on a place that should have what I need. I was told they have thick industrial cast plate at scrap prices and even have the facilities to cast their own. The place is 2 hours away, so i'll give them a ring tomorrow, and make a trip this weekend if it looks promising.

Cool! Keep us informed. Maybe they have a stream of rejects or something that can be repurposed for our little machines.

If all else fails, I might end up just using the stainless plate as the table. It is very flat, so I might get away with using it as-is.

Some of will cry knowing that a big slab of stainless is acting as a table for a CNC router.

[l3viathan]

I couldn't resist, these road plates are just about impossible to miss around here. What can I say I needed the humor.

I know what you mean, luckily, I haven't run across any in a while.

Cool! Keep us informed. Maybe they have a stream of rejects or something that can be repurposed for our little machines.

Well, the guy that recommended the place said that he recently bought a 4' x 8' steel plate .75" thick from them for 50 cents a pound. How's that for a deal?

Some of will cry knowing that a big slab of stainless is acting as a table for a CNC router.

Since I got it for next to nothing, I had to look up the retail on it...and my jaw dropped. I actually felt kind of guilty thinking about using it as a table.

[l3viathan]

Since i'm still working out my Z-axis design, I got to thinking about the actual spindle mount. There seems to be two major types: the kind with a single split that a bolt(s) draw together shrinking the ID, or the two piece that sandwiches the spindle between two semicircles. I'm thinking that the single split kind probably grips more evenly, however it doesn't really work in the setup i'm going for. I liked the looks of the OpenBuilds spindle mount, so I modeled this up quick.



My concern is that most of the holding will be done with the front and rear of the clamp, and may not be as good as the other type(s).

[wizard]

Since i'm still working out my Z-axis design, I got to thinking about the actual spindle mount. There seems to be two major types: the kind with a single split that a bolt(s) draw together shrinking the ID, or the two piece that sandwiches the spindle between two semicircles. I'm thinking that the single split kind probably grips more evenly, however it doesn't really work in the setup i'm going for. I liked the looks of the OpenBuilds spindle mount, so I modeled this up quick.



My concern is that most of the holding will be done with the front and rear of the clamp, and may not be as good as the other type(s).

One set of lathes I use to work on had the mounting hole for the air bearing spindle lapped to fit. It didn't take much at all clamping wise to lock,the spindle in place. Taking a cue from that and the spindles on many a Bridgeport I'd suggest that the closer the fit the better the clamping action.

The final design obviously plays a role in how well the mount will work, nut I'm going to suggest that a spit ring design will be better. That is a design with a single slit that gets pulled together to clamp the spindle. A two piece design would probably work if you could get four bolts into it. I'd be considered about the bolts rocking on a two pice design if only two bolts are used to clamp the spindle.

In either case a simple ring won't do the job as well as two spread out over the length of the spindle assembly.

[l3viathan]

My plan was to bolt this through in the back (2 x 10mm) and bolt through the sides as well (4 x 6mm) to "box in" the spindle, and stiffen the axis overall. I did plan to use 2 of these spaced well apart as you noted. In planning how to actually make these, I was thinking of making both mounts from a single piece, so I could bore the center to 80mm, and run an engine cylinder hone to bring it out to a nice close fit. Then cut the block in half to have two matched pieces.

I figured the split ring design would grip better, but I imagine that it pulls the sides in some small amount to work, and with the mount boxed in, it may be to some degree less effective. I think i'll model a split ring version of this, and run some FEA to determine exactly how much the sides deform to clamp a spindle.

[l3viathan]

I'm finishing up the design for my Z axis, and thought I'd post it here for any feedback. It's derived from the Datron M8Cube design. I plan to put a metal cover over the front (which will bolt into the carriage sides) to box in the larger carriage plate.

[l3viathan]

Hopefully, I'm not spamming too many posts on this thread today, but I just put the z-axis assembly on the rest of the machine. I think the design is looking pretty good so far.

[yellow68gto]

I love this machine. The similarities to my design are awesome. I just am not seeing where/ how the ballscrew is mounted to the spindle carriage. I need to do a update to my thread. Picked up a bunch of my material

Sorry side tracked.

I really like the carriage idea. Should be plenty rigid

[l3viathan]

I just am not seeing where/ how the ballscrew is mounted to the spindle carriage.

Here the the Z-axis with the motor mount removed in an x-ray view, which shows the ballnut mount.



edit: I can't wait to see how you have your design set up. Post those CorelDraw pics!