The plan is to build a sliding table type router table for making
raised panels for doors on a furniture project. I am going to use a
couple of linear bearings on shafts attached to a large aluminum plate
for the sliding table, then use an 3/8" x 10 tpi Acme precision lead
screw to advance the sliding portion of the table. The plate will have
the wooden workpiece attached and feed the wood hanging off the edge
into the panel raising bit. The last time I raised panels I sent a
couple of workpieces across the room because they weren't fixtured well
enough to my plywood jig, so I really need a rigid sliding table for
safety and better results.

I definately don't have the skill or thread cutting attachements to
make my own lead screw and nut, and the prices on a complete assemby
with support flanges and flats milled on the leadscrew are pretty
steep. So I am looking at just buying a 3' length of lead screw with
an oversized nut. My question is about how to finish the ends of the
lead screw. Can I just weld a sleeve, with a tight fit between the OD
of the screw and the ID of the sleeve, over the ends of the lead screw
- then slide that into a pillow blocks to support the ends of the lead
screw? Of would I be better off trying to chuck the 3' lead screw into
my HF 3-in-1 and turn the screw shaft down to a smooth round surface
that fits into a smaller bearing in my pillow blocks? I have never
tried to turn a threaded rod and don't know if the threads would catch
on my cutter. I'm quite new to machining metal, and could really use
some advice.

thanks
James B

wrote:

Of would I be better off trying to chuck the 3' lead screw into
my HF 3-in-1 and turn the screw shaft down to a smooth round surface
that fits into a smaller bearing in my pillow blocks?

Yes.
Hope the chuck is centric. And the lead screw is going through your
spindle.
It may happen, that the other end will start to vibrate, bend and then
slam everything into pieces coming into its way. It is best if you put
the free end into a (quite bigger) tube that is well fixed to some heavy
whatever.
I won't tell you the other trick. :-)


I have never tried to turn a threaded rod

Many did before you! :-)


and don't know if the threads would catch on my cutter.

Not at all. Do it like you would do it with a smooth surface.


Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

wrote:
The plan is to build a sliding table type router table for making
raised panels for doors on a furniture project. I am going to use a
couple of linear bearings on shafts attached to a large aluminum plate
for the sliding table, then use an 3/8" x 10 tpi Acme precision lead
screw to advance the sliding portion of the table. The plate will have
the wooden workpiece attached and feed the wood hanging off the edge
into the panel raising bit. The last time I raised panels I sent a
couple of workpieces across the room because they weren't fixtured well
enough to my plywood jig, so I really need a rigid sliding table for
safety and better results.

I definately don't have the skill or thread cutting attachements to
make my own lead screw and nut, and the prices on a complete assemby
with support flanges and flats milled on the leadscrew are pretty
steep. So I am looking at just buying a 3' length of lead screw with
an oversized nut. My question is about how to finish the ends of the
lead screw. Can I just weld a sleeve, with a tight fit between the OD
of the screw and the ID of the sleeve, over the ends of the lead screw
- then slide that into a pillow blocks to support the ends of the lead
screw? Of would I be better off trying to chuck the 3' lead screw into
my HF 3-in-1 and turn the screw shaft down to a smooth round surface
that fits into a smaller bearing in my pillow blocks? I have never
tried to turn a threaded rod and don't know if the threads would catch
on my cutter. I'm quite new to machining metal, and could really use
some advice.
You'll need to fabricate a support for the far end of the leadscrew.
This can be something pretty simple lashed together, with a piece of
water pipe to hold the end of the screw. Better make sure the screw
can pass through your spindle hole! You won't have to worry about the
cutter "catching' on the thread. It will be an interrupted cut, and a
bit rough, but it should be able to do it unless the screw is hardened.
If you are buying Acme or allthread stock, it won't be hardened.
Put the screw all the way through the spindle, so only an inch or so
is sticking out of the chuck. That will give solid support to where
you are making the cuts.

You may want to rig a Dremel tool or air die grinder to the toolpost to
finish the ends. (A toolpost grinder is the tool of choice, but I doubt
you have one of these.) You put a small grinding wheel on the tool and
grind the OD and flange of the leadscrew to proper dimensions with a
fine surface finish. Depending on the screw material, you MAY be able
to cut it to a good finish with cutting tools, but it is not guaranteed.
Removing the last .001" by grinding will give accurate dimensions and
a fine finish for sure. (Protect the lathe from the grinding dust with
damp cloths.)

Jon

wrote:

... use an 3/8" x 10 tpi Acme precision lead
screw to advance the sliding portion of the table. ...

Do you really need a lead screw to advance the table? Can't it be
advanced by hand (pushing)? The 10 tpi lead screw is going to take a
*lot* of turning (180 turns for an 18" edge). Bob

Use a bicycle chain and sprockets. Very little slop in those
I have some Thompson linear bearing pillow blocks recirculating ball
type for .5"
shaft. Model pb8a
I'll sell em for 60% of what the bearing places charge.Pls shipping. New
in box, 4 pieces.
Email me off-group
Thx
Dan

It's a bit hard to understand why you need precision leadscrew accuracy
for a woorworking router table. Why not just some hardware store
threaded rod?

John Martin

Multiple reasons really. Mostly, I tried to build something like this
before using plywood, full extension drawer slides, and generally cheap
components, and it shreded my workpiece pretty good. I want to do it
right this time. An ME could maybe explain better, but the Acme
screws have a vertical face will push my table the direction I want it
to go, while the hardware store rods have the "V" shaped threads that
will transfer some component of the applied turning force in the wrong
direction for my application. I think the "V" threads are designed
more to hold a night at a high torque than they are to advance the bolt
on a rotating shaft. Plus a small threaded rod that my drill could
turn would bend when the router bites the wood, and a thicker rod would
smoke my drill trying to turn it.

Part of where I need the accuracy is in controlling the feed rate. If
the feed rate is to slow the bit will burn the wood deeper than can be
sanded away, and if it is too fast I will burn up router number 5.
Another place where you need accuracy is stopped dados and sliding
dovetails. If you look at something like the Incra jig for routers, it
uses a lead screw just for the fence. And mostly I want to might want
to use this sliding table as part of a stage some other CNC project.

I won the bid last night for linear bearings on 3' shafts, so parts are
on the way. I will try to post a link to a picture when this is
finished.

- James B

Thanks for the offer, but I am going to try to fabricate pillowblocks
to hold rollerblade roller bearings. And having fed these raised panel
doors by hand previously, I know they can jerk violently in any
direction. I have some small shaft mountable sprokets and chain laying
around, but am afraid the difference in slop between the Acme screw and
a chain would be enough to tear out the wood on my workpiece. I like
the chain feed idea though, if I make a sliding table for my table saw
that would be a good way to drive it.

- James B