Dovetail slides

[coolman]

Does anyone know how to make or buy those dovetail slides that is common on Metal Mill machines? Is there a way to mount one piece of the dovetail slides on a flat plate and mount the matching piece to the CNC routers bottom frame? Each piece of a dove tail slide can be a long piece of metal bar with a dovetail shape which is easier to install or make than milling a large piece of metal block which is used for both the table and slides. I am not sure if I am explaining things right here. Any comments?

[A. Shuford]

Some years ago I built a unit like you are talking about. As a matter fo fact, I think I sent it away just a few days ago with the junk man. I took a piece of plate some 4x8x3/4 and milled the face flat. Then I used something like 1x1 1/2 flat cold roll and milled a 45 degree bevel on them. I bolted these to the plate. I then mounted all of this in my mill and made a finishing cut so they were parallel. Then I cut two slides the same way and mounted them on a stationary plate.

It took some time but the end result was pretty nice for an old country boy.

[JFettig]

Take a look around for dovetail cutters, that is how most are made. I have one that I bought from Grizzly, many other places have them.

The only thing about using dovetails is that it takes a lot more to push if its going to be really rigid(tightened gibs).

Jon

[BigDaddyG]

I agree, dove tail cutters are made for such a thing. The trick comes in with the gibs. If you look at most mini mills, they are cast iron. Look at making a Bronze or Brass gib, they are a bear to cut, but once done your dovetail will preform like a champ!
Regards,
Glen

[HuFlungDung]

Coolman,
I would not recommend piecing together a dovetail slide out of....pieces. You'd be losing the only advantage (if any) that the dovetail gives and that is rigidity. This is because only the bolts that bolt it down would be doing the holding. You might as well use a premanufactured linear rail.

Having cut a few dovetails, I can tell you that those dovetail cutters are a pain to use. They are very delicate. Its not like you'll want to hog the whole thing in one pass. So, then, you'll be using just a bit of the tip of the cutter, and by the time you get down to the finishing pass, it will be dull at the tip and sharp further up

If you mill steel, it's really hard on the cutter. Aluminum probably is not even a choice because it will score and seize in no time. That leaves cast iron for the material, and that is not likely easy to come by.

"Real" dovetails used on machine tools are works of art. They often use a very long tapered gib to adjust the clearance. (cheap dovetails use a simple multi- setscrew gib adjustment) A matching dovetail taper angle has to be machined in one side of the female dovetail. I haven't been able to figure out how these guys hold them to machine them. If anyone has cut one of these tapered gibs, please send me one of your boots to worship

[ViperTX]

Originally Posted by coolman Does anyone know how to make or buy those dovetail slides that is common on Metal Mill machines? Is there a way to mount one piece of the dovetail slides on a flat plate and mount the matching piece to the CNC routers bottom frame? Each piece of a dove tail slide can be a long piece of metal bar with a dovetail shape which is easier to install or make than milling a large piece of metal block which is used for both the table and slides. I am not sure if I am explaining things right here. Any comments?

Other then educational...why would you want to pursue dovetails...linear rails or linear bearings are the best way for a home machinist. Not criticism...just wondering....

[Al_The_Man]

Originally Posted by ViperTX .why would you want to pursue dovetails.....

I would assume he wants to have the rigidity and mass of a heavy dovetailed table, rails are ok for the lightest of cuts, but if you want to hog metal, the typical mill table wins out.
Al

[coolman]

I am trying to build a metal router to do wood and metal projects on. The dovetail is sturdy, rigid and the commercial mills use them. Linear rails/bearings like THK can be expensive. If I can buy these dovetail pieces, then I do not have to mill one. Right now, I am just exploring the possibility of using dovetails.

[fyffe555]

Reid tool supply www.reidtool.com list some smaller iron dovetail slides - page 386 on thier pdf catalog. They're not cheap, but then neither are some of the alternatives...

[ViperTX]

SKF also has dovetail slides:
http://www.rtgilman.com/slides_nd.html

[DareBee]

Maybe the easiest way would be to buy an old mill or lathe (before it goes to scrap) and cut a section of slideway out of it.
Otherwise I would build square ways. They are (theoretically ) easier to manufacture and much stronger than dovetails.
By theoretically I mean the processes are simple and straight forward but grinding them to perfect tolerances and working the warp out of them can be tedious.

[ESjaavik]

Hu Hi,

Set up the female tail to be and the gib in 2 (holding de)vices on the table.
Cut the female slot to the small end measure and the gib to the big end measure. Then angle up your table and cut once more on the side of the female slot that is facing away from the dominant force when in use. And cut the appropriate side of the gib strip. One side of the gib must of course be cut with a cutter where the coned angle is inverted. On my machine this can only be done in the Y direction, thus not very long. Otoh the head can be tilted instead of using the mentioned reversed cutter. Doing it this way it just have to fit since the angles are made in the same setting.

Now the piece o fart comes when scraping them in. You should have a lot of patience. Ask your wife if you have talent for this. The reward for the fettling is a silky smooth slide. It's a great feeling when you get it right.

If you can't cut the female and the gib in the same setting, you'll have more fun when scraping them in.