I would mount the 1F directly to the steel top - that 1" plate is more than sufficient to keep the 1F in square, in plane and rigid.
Then take the MDF pieces and cut them to the 48x32" cut area size for the JM. Pin them together with brad or pin nails. Run a V-bit manually with just the lightest touch to mark the outer limits of the JM cut area on the steel. You’ll use those marks to line up the MDF. Put the MDF on the steel and clamp it down so it’s held in place - regular woodworking clamps placed on the edge would likely work fine but you can also use double-sided tape or blue tape/CA glue (wash the steel top with acetone or denatured alcohol to remove all oils before you try using tape).
Run you hole boring job to a depth of about 1 3/8" or 1 7/16". That will bore the holes through both layers of MDF. Mark them so you can align them again. Then using brass barrel inserts (not t-nuts) install the barrel inserts into the lower board. Mount it using bolts (recess the bolt heads) in the steel tabletop. Place the top piece of MDF on the bottom piece and insert several 1/4" bolts (assuming you used 1/4" barrel inserts) to get the alignment spot on. Screw the top piece to the bottom one using 1" brass wood screws countersunk into the top.
You’ll be able to resurface the top piece pretty often before you’ll need to reset the wood screws holding it to the bottom piece. You also won’t have to worry about hitting one of those screws when flattening since the brass is much softer than the carbide mill. The same is true if you ever go too deep on a milling operation and send your end mill through the top piece of MDF into the bottom piece.
When you’ve resurfaced the top to where it won’t hold up anymore, just replace it with a new piece, use your boring file to go .752" and you’ll have another fresh spoil board.
I was originally considering something similar to what you describe in the sense of two boards and the JM mounted directly on the table top (although you did an amazing job of articulating how it can be done). I shied away from this approach because I figured I would lose 1.5" of z travel and in my situation, I need all the z travel I can get (I often work with chainsaw cut tree rounds and sawmill cut planks). Plus, I am not confident of my metalworking abilities to make sure I don’t screw something up in the hole drilling that can’t be fixed. I am glad I at least practiced on MDF and found that the left side of the JM needs more space than I gave it.
Since I am not always working with dimensional lumber, I need hold-downs that don’t rely on tape and ca glue (although I will use that whenever I can with flat lumber). For me, I concluded that I would need t-tracks and/or threaded screw inserts and dogs.
From what I have heard from others, the threaded screw nuts pull out of MDF too easily, which is why ended up going the route of t-nuts, not only for the screw in fixtures, but also for the t-tracks. However, doing that makes things more difficult to deal with because, as you pointed out, I can’t just bore through both top and bottom layers at the same time as I can with your approach. The countersinking the flange on t-nuts makes this more challenging.
you could still mount the Onefinity on the steel table top but omit the wasteboard. A wasteboard is only needed if you plan to mill deeper than your workpiece (intentionally or unintentionally ). In the milling metal world, there is nothing like a wasteboard and it is the question if it is really necessary in the milling wood world. Some people here have metal workplates, e.g. Bill @Machinist (steel with threaded holes, shown here and here ), Tom @TMToronto (Alca5 aluminum, to see here and here) or @alldaysammyj (aluminium extruded profiles, to see here). Okay they don’t seem to mill wood, but just to show how it looks like. What you need is of course something to attach your workpiece. This could be done by an array of threaded holes in the steel table top. If it’s steel, it has the advantage you can really drill the threads into the plate (unlike into an aluminium plate where the threads will suffer too much wear when under load). With these threaded holes you can use the usual hold downs or you could use vise-like clamps that hold from the side (like here or here) OR you could use wood screws into the bottom of your wooden workpiece that go through the table from the underside. And you could still use a wasteboard on top of the steel table top if you’re not forced to use the entire Z travel (e.g. as shown here).
In this post you said it’s granite? 1 inch is extremely thick. Are you sure it is steel? If so, do you know what type of steel it is?
Yeah, that was another thought i went through. I dont have the capability to do it myself, so I went to a local fabricator. For a 2 inch grid pattern tapped with 1/4"-20 threaded holes, he wanted close to $700, possibly more. What made me even more concerned was that he could only guarantee 1/32 accuracy, and they would do it by printing a paper template and then drill the holes manually (with a press I assume). No CNC. That would mean when I go to drill a wasteboard that sits on top, there would be no guarantee the holes would align. By the edge of the board, I could be way off. Besides, the top itself is in 3 segments (front, middle, back) that also need to be properly aligned. So many points of failure to contend with.
The only way I could even consider doing it myself, would be if the JM did the drilling in the table and then I did the tapping by hand. That may be an option down the road once I get a chance to try a few things and know what I can and cannot do. I dont have a spindle, so if I was going to try to use the Makita router, it would be an extremely slow process. I am wondering if I would have to take cooldown breaks between each hole.
Can I use a metal drill bit (and oil) instead of a router bit and just plunge straight down? I don’t need to shape anything…just bore a hole.
Yeah, the son, who was selling it for his dad, said granite, but when I saw it, it was clearly metal. Whether it is steel, cast iron or aluminum, I am not 100% sure. It is painted/powder coated so hard to tell. What threaded holes it does have (very few) are not shiny, so I am guessing steel or cast iron. No idea what hardness it is either. It is exactly 1" thick. The three panels together measure 70x64. I would guess that it weighs somewhere around 400lbs. It took 2 people to lift the middle panel which is 70x32. The other panels are 70x15 and 70x17. I could lift them, but was a little worried about my shorts. They were very heavy to say the least.
Wow, no CNC, no accuracy, and then such a price. I think I would not consider this offer.
If you have a CNC on top of the plate (I assume you found the positions to drill the holes for the four feet now), it would sound like madness not to do the drilling job with the CNC. But unfortunately neither the Makita trim router nor a usual 6,000–24,000 rpm spindle would spin slow enough to do the thread cutting job, and for the drilling job for the router it’s at the limit but worth a try on a sample workpiece. The Makita gets hot on low speeds (a spindle not, but you said you have none). I assume you don’t have the money for a spindle specifically for drilling .
Here you can see once again that the manufacturers of the Onefinity lack foresight as to what benefit and what success a 43 mm mount would bring. With such a “Euro” mount, one would not only have a variety of milling motors as AMB (former Kress), Suhner, Mafell, etc. to choose from, but also a drilling machine with reduction gears. You could cut threads with it (in the lowest gear). I think when I will have my machine ready, I will try to mill a 80 mm → 43 mm reduction ring from the solid aluminum to be able to use such machines. Maybe for a drilling job at low speed, a 3D-printed reduction ring will do it.
Alternatively you could buy this 43 mm mount and file off the overhang until it is 80 mm in diameter so that it fits into Onefinity’s mount. It’s already 80 × 80 mm in size! Then you can mount your drilling machine with its 43 mm neck and drill the holes with a moderate rotation speed.
Anyway if you decide to do it, I would try it with the Onefinity, for the drilling job, and if nothing else is available, with the router, at the lowest speed and with cooling pauses. I would start with a very small metal drill bit (e.g. 2 mm) and then enlarge all holes with drill bits in 1 mm increments until the desired size. And with cutting oil, sure.
Note that for the tapping job, you not only need very slow speed (much slower) but also the ability of the machine to run in reverse direction (to leave the hole after cutting). So a usual electric drill with reduction gears is usable if you have speed regulation (in addition to the reduction gears). A spindle can run in reverse direction but you would need a very specifical low speed spindle.
Also I would not cut threads free-handed, but use a drill stand like this which you can move around everywhere on your tabletop. It allows more precision for vertical accuracy.
Here you can see a manual tap machine at work. You see that the operator switches into reverse rotation to leave the hole. The ugly noise that you hear when they finish a hole is the mechanical torque limiter which is necessary since they tap blind holes.
Note that when you cut threads with a machine, you need special machine taps that differ from those for manual use.
The magnet test? Steel contains iron which is ferromagnetic (as long it’s not austenitic stainless steel, which is not).
I would only tap holes if it’s steel, not if it’s aluminium. In that case I would use threaded steel inserts from the underside.
another thing: Before deciding on where to position the machine, if you ever plan to use drag chains, take into account the additional space. If you ask me personnally, I would rather have the stepper protruding the right acrylic (or polycarbonate?) pane than to loose the option for drag chains. For Journeyman drag chains components, see here and here
Note that as long you don’t use drag chains, the stock cabling lacks strain relief on the Onefinity CNC (except the little crimped strain relief on each individual contact pin). Especially on the moving X gantry, the permanent movement is not good for the cables on the connectors which is why many people added 3D-printed or wooden strain relief and showed their solutions here. I would in any case at least provide space for this.
I rented a mag drill to drill the holes I wanted in my aluminum plate, using a large sheet of steel under it clamped to the various positions needed. It might work well for you as you have a steel plate already. Instead of the annular cutter I rented it with the drill chuck attachment. It had a bit of runout, but worked for both the drill bit and flat bottom counterbore.
I could not afford the quotes I got for having the holes CNC drilled and tapped, so found this method cost effective and accurate enough for my application as the threaded holes are used to mount aluminum T slot extrusions. You may need/ want greater accuracy and precision.
You could put riser blocks under the JM’s feet. I think a couple people have posted about doing that here. You could just use a couple of layers of MDF and make some 2x2 or 2x3 rectangles and through bolt them under the feet when you mount it to the steel - no loss in height
Maybe they do but I’ve found that most people overtighten their clamps and fixtures. (It’s the same with tightening the collet nut with the wrenches - snug, not monkey-tight!)
You could do t-nuts but in that case I’d treat the “top” sheet that I was boring out as the bottom sheet when I ended up mounting them. Simply do both the through boring and the countersink operation for the t-nut. Then when you need to replace the spoil board you’d skip the countersink toolpath.
If you want to do t-tracks, I know there’s a lot of ways to cut the track groove but I would skip that altogether. Just mount the lower board on the table top. Then you can run a groove cut for the bottom of your “tracks” big enough for the t-track bolt heads. Next I’d slice the top board into strips using a tablesaw so they overlapped the lower board’s grooves enough so a t-track bolt head wouldn’t fit through but the qtr inch bolt shaft would. Then you’ve got an MDF t-track for free
You could also skip cutting your top board into slices and just groove it once it was attached to the lower board. The narrower bit will overlay the center of the lower “track” and you’re good to go. In that case you’d need to make sure you’ve attached the top board with sufficient brass screws or pin nails across the width to make sure they don’t come loose when you cut the slots.
In either case, you’ll have 3/4" of MDF from the top boards providing the stop against the upward force placed on the t-track fixture bolt heads which is certainly sufficient. You don’t really need the aluminum track structure.
If you really must use aluminum t-track, you can create a grooving path for the lower board with an inset to cut the top board. Because they’re part of the same carving design file, they’ll line up fine. You can cut them with the boards not attached (do the wide cut through the lower board, attach the top board and then ignore the wide toolpath but cut the narrow one through the top board) or do them both attached to start (do the narrow cut through both and then remove the top, do the wide cut and replace the top board). You can also do it with the two boards attached by using an appropriately sized keyhole bit but that’s just any extra bit purchase needed.
PS: I would try to use the Onefinity CNC for drilling the holes (even if only with the router), because then you don’t have to measure, mark and punch a hundred points , additionally to still have to finally bore them one by one. But if you decide to do it manually, with a drill stand like these and an electric drill, or with Tom’s idea, a mag drill, I can recommend this Starrett Automatic Center Punch #818 that I use. There are also some models with steel handle in different sizes.
If you want to tap the holes by hand, these Star-M drill stands with drill chuck are ideal for this.
Is this setup, with the tie downs and drag chain, still going to be a problem with cable rubbing and fraying?
I can certainly move the machine over closer to the right, but the limitation is the aluminum frame not the polycarbonate/acrylic enclosure panel. I have two middle bars that the motor needs to clear.
I don’t have a magnet here, but found one in the JM dust boot. Yeah, it is an aluminum top.
The more I think about drilling the top, the less I am fond of the idea. Another reason is that the mounting bolts on the 1F feet have some play in them. Which means, if I ever did unmount it, my holes in the top would be off. I think I will have to stick with something that I can re-do whenever I unmount and re-mount it.
I like this idea! To be fair though, t-tracks are relatively inexpensive. What is the killer are the tee nuts and screws. I spent over $250 in just tee nuts and screws that would be peppered throughout the mounting board.
I am beginning to wonder if I would be better off just installing t-tracks and dog holes and forget the screw inserts. That would dramatically simplify this whole process. I would not have to countersink the t-nuts, nor would I have to worry about two sided milling. I just bore the dog holes almost to the top of the table and screw the t-tracks into the lower sheet (or maybe even the table top), and be done with it!
I am going to have to ponder on that a bit more, and see if I really do need to have screw based fixtures. Anyone not using these but wish they did?
this easy to solve. You simple use bolts with .315" thick shaft (8 mm), or thinner bolts on which you slide sleeves (=hollow shafts) with .315" (8 mm) outer diameter. And voilà, no play anymore, perfect repeatability guaranteed.
However should you ever upgrade to a spindle with its thick shielded spindle cable (up to 12 mm diameter) and two water coolant hoses (8 mm each) and maybe shielded signal cables for two inductive homing sensors, and maybe cable for a milling area ring LED light, and one for laser, etc., usually you would add 50 mm (~two inches) to the left of the X gantry.
The tie prevents the final part of the cable to move, so it should act as strain relief. Important is that it immobilizes the cable end absolutely during Y movement.
It’s not rubbing and fraying, the lack of strain relief on a cable produces this:
Oh! Yeah, that is not good! Even though it currently fits, I will move the machine to the right as much as possible to allow larger drag chain in the future, as I do eventually want to go to a spindle.
Ok, so here is where my head is at now, thanks to all the help and wonderful postings!
First, mill out a channel in the bottom board to install t-tracks, then screw them into the channels.
Next, bore the holes which will have tee nuts for keeping the two layers together (only 8 per wasteboard panel) almost to the table top.
Disassemble everything, and manually finish the tee nut holes as well as drill the countersinks.
Next, cut out the wasteboard panels that will form the second layer. The panels will be slightly larger so that they overlap the t-tracks as shown here:
Next, clamp the wasteboards down as shown above and bore the countersink holes for the brass screws that hold the two layers together into the tee nuts. Install the screws and remove the t-track clamps.
Next, bore the dog holes and the screw insert nuts almost to the bottom of the lower board.
Then, remove the wasteboards and install screw insert nuts (not tee nuts as Jim Hatch suggested), hoping that the flange on the inserts is held in place by the upper board (again, similar to the above picture, only with insert nuts).
This way, I don’t have to do any two-sided milling and I get to keep screw fixtures, dogs and t-tracks
When a wasteboard needs replacing, I mill it out, unscrew it, and drop it in place. Everything should align perfectly.
Technically, I don’t need the dog holes in the lower layer, but I thought it might be a good way to force alignment when fixing the two layers together and allow a little tolerance in the screw holes.
Anyone see a problem I didn’t address?
Thanks for all the wonderful ideas and suggestions…I have taken bits of each and might just have a decent solution! Thank you all.
Oh, and I forgot to mention…the reason for doing it this way is so that re-assembly of the JM doesn’t impact the alignment of the two layers. These are drilled after re-assembly, and the machine will not be moved again.
Yeah, unless you were to get the bottom pretty flat using a bandsaw perhaps, clamps would be the answer. I’d use eccentric cam clamps so you can tighten against the uneven roundness of the cookie. You can get (or make) cam clamps that use either dog holes or t-track.
At the lowest projection, only 5/8" of the dog head is above the bench. The swivel handle lets you apply ample clamping pressure in any position. The dog is drilled and tapped at a 3° angle to ensure that work is held tight to the bench.
Ok Aiph5u! You are extremely knowledgeable and resourceful without a doubt, but damn if you are not killing my wallet!
Those look pretty awesome, and I love how the avoid tearing up the holes with the split shaft and a 5 degree angle. I am keeping those in mind for sure if I start having problems with my milled ones. I am going to try to make my own first and give it a whirl (hopefully “whirl” doesnt end up referring to my stock. )