Re: MM Mark 2 (nothing store bought except steel)
- --- In firstname.lastname@example.org, "David G. LeVine" <dlevine@...> wrote:
>Read these plans first so that my drivel is more understandable.
> Comments in line.
> Pat wrote:
> > In the photo file "1 MultiMachine Mark 2" I added 3 drawings of a new carriage. I based the design on 3 successful ideas. A conventional lathe saddle and the "Romig" turret lathe and horizontal mill plans.
> >I have fought import gibs so much! Home made ones could be even worse!
> > Specifics:
> > All the "ways" are Romig style box type with no "v"s or gibbs. Adjustments are done by loosening bolts and tapping with a small hammer.
> You may be wiser to use gibs and setscrews, the "calibrated hammer" may
> work, but it depends on the user a bit too much.
>A lot of these protrusions can be removed by an angle grinder.
> > The lathe ways (bar stock) are 6 to 8" wide and bolted to the block. 6" ways would need a filler strip underneath for clamp clearance.
> And, depending on width and protrusions, the 8" may also. Your block
> and mine will be different from one "found" in the jungle.
Quite right. I think 8" should be the minimum because of the overhang of the wide carriage
>I totally agree.
> > The cross slide would be 14 to 18" wide and would be made from 6" x 1/2" bar. (always remember that "real" horizontal mill slides may weigh over a ton)
> 6" x 1/2" bar may be too weak. Consider a different form factor. Heavy
> angle or I-beam can be more rigid. If vibration is a big issue,
> non-shrinking grout can be a savior.
>Probably so. I was trying to keep the steel cost as low as possible. One thing though, I have rarely needed much travel, others may need a lot more.
> > A lathe "compound" could be added on top as could milling machine ways but are not necessary at first. Tapped 1/2" holes could be used for the lathe tool holder or milling vise.
> As is done on "tooling plates" in the CNC industry.
> > For economy in the use of steel, the vertical slide could have only 6" travel.
> You probably will need more. However, it is your design.
>I was trying to make everything as cheap and simple as possible. A 1 1/4" arbor is a pretty stout sucker. I would rather have the fattest spindle possible but the 1 1/4" spindle/arbor combination should be considered if there are cheap horizontal cutters available.
> > The spindle would be 1 1/4" (common Ebay horizontal mill cutter size) shaft or a piece of 1" heavy wall pipe turned to that size. A cast iron of steel (scrap) faceplate could be brazed on the spindle end and finish machined in place.
> I wouldn't do that. Shrink fits are as secure and don't have as much
> distortion. 1-1/4" is pretty light for a spindle, I would want to see
> at least a 2-1/4" OD (see http://www.workholding.com/SPINDLESPECS.HTM
> for common spindle threads.) Remember, you can always make an arbor for
> mills which are SMALLER than the bore.
> Another good technique is to make a tool holder mount and have the arbor
> pulled into it by a drawbar. R-8 collets are often used for that, 5C's
> are cheap and much better than setscrews, ISO-40 tool holders
> <http://www.techniksusa.com/wood/isosk.htm> are good choices (they are
> 2-1/2 inches OD roughly), and ISO-30 tool holders look to be strong
> enough. Why? They are easily available.
> If you want to stay with Morse taper sockets, there are sockets like the
> ones here
> which should be pretty simple to build a mount for. They will need a
> drawbar to hold them and a key so they don't turn.
> > The end of a solid spindle could be drilled end 3/8" shaft end mills or a spindle for a drill chuck. The face plate would be thin enough so that the set screws needed to retain the mills/chuck behind it.
> Or just mount a collet.
> > Home cast bushings of piston metal or ZA-12 or 27 would allow spindles to be interchanged.
> > So that's it, Nothing storebought except steel, no outside machining unless you need to turn a piece of pipe down to size and no welding except for one braze job.
> > Pat
> Actually, a good plan, but there will still be needs for some other
> "store bought" parts, like all-thread.
>What I was shooting for was a flexible machine with steel costs around $100 and no outside machining. Your shrink fit idea is great but I don't see an easy way to bootstrap it by a semi-skilled worker.
I checked around today and got a steel cost about $125 for everything.
Many thanks Dave!
- Mercifully stripped to make the inline contents findable.
> Read these plans first so that my drivel is more understandable.Will do.
> I have fought import gibs so much! Home made ones could be even worse!Gibs can be as good or bad as the maker wants them to be. Given 10-32
(or M5) cone point setscrews with nylon patches and locknuts, the
adjustment can be pretty easy. Normal cup point setscrews are really
bad, they are designed to dig iin, and as they do, the gibs
self-loosen. Dog point screws are better, but the recesses become
tricky. Cone point setscrews with the correct bore are really good, but
not cheap (which is why the imports are often other than good cone points.
>>> For economy in the use of steel, the vertical slide could have only 6" travel.Sometimes false economies can hurt more than help. If there are 3" and
>> You probably will need more. However, it is your design.
> Probably so. I was trying to keep the steel cost as low as possible. One thing though, I have rarely needed much travel, others may need a lot more.
6" cutters on eBay, how much travel is left? I would expect the the
knee to need closer to 12" of travel with 9"-10" to be minimal.
Remember, this machine will need to do flat stock as well as repair
small motors (like B&S) in the 8HP and smaller sizes. Measure one and
figure how high the top of the cylinder goes.
> I was trying to make everything as cheap and simple as possible. A 1 1/4" arbor is a pretty stout sucker. I would rather have the fattest spindle possible but the 1 1/4" spindle/arbor combination should be considered if there are cheap horizontal cutters available.Oh, I agree. However, cheap cutters can come in many sizes, it is often
better to design the machine to handle a range, even if the initial cost
is higher. Imagine a hollow spindle with a taper in the front and a
drawbar to pull in the adapter. Now, put an arbor on an adapter into
the spindle. The arbor is as rigid as the spindle, a good thing. You
can have 3/4", 7/8", 1", 1 1/4" and 20 mm arbors which interchange.
Since the spindle will be machined anyway, the addition of a taper is
not such a big deal. Given a compound, it can be machined in place as
one of the first operations. By all means, make a solid, hard mounted
(welded, brazed, shrink fit, or Loctited) face plate and machine it in
place, but keep the thought in mind, setting up a precise spindle and
machining the bearing and pulley areas is not trivial, cutting a
non-self locking taper may be easier.
> What I was shooting for was a flexible machine with steel costs around $100 and no outside machining. Your shrink fit idea is great but I don't see an easy way to bootstrap it by a semi-skilled worker.The best thing I can do is provide a good sounding board for you. It
> I checked around today and got a steel cost about $125 for everything.
> Many thanks Dave!
limits the dead ends.
Let's assume you can build the machine except the spindle for $125.00
(and, no, I don't think you can.) With the spindle being just a hunk of
DOM tubing sticking a foot out of the headstock, you can machine it to
length (face turning after cutting), turn the end ID to fit a rod which
fits an ID in a barbell weight, turn a recess in the barbell weight to
fit the end of the spindle and shrink it in place. Turn the barbell
weight to make a faceplate, possibly deepening the recess. Cut off the
end (the rod was forced in anyway and the end probably is not very happy
right now), make a final OD/end cut and mount the faceplate with the
finished side to the headstock, turn the front to fit your "plain back
chuck" and machine the taper in the spindle ID after the faceplate is
mounted. If the bore will take a standard collet, make a permanent
center in a collet. It can be replaced any time you need since the
collet is located by the hey (see R-8 and 5C collets for the way this
Now you have a chuck and faceplate mount and a spindle which will take a
collet or arbor.
PULLEYS ARE EXPENSIVE! Consider a larger OD spindle driven by a
serpentine belt. Inside out until you can machine the necessary grooves
in the spindle, then back to the max torque configuration. Serpentine
belts are generally more expensive than V belts, but the costs of a
pulley (even cast in place) are not trivial.
Just a bunch of brainstorming here...