Stefan Trethan wrote:
ground hardened steel, exactly as you describe. I haven't
measured the round out, but its definitely not visible.
This is the standard way collets are built. Collets in the Dremal
are a cheap and nasty version. I'm just glad the store I bought
the Dremal from gave me my money back when I returned it.
I'm not sure about double bearings on the end of the motor shaft.
I think the grinder I bought has one ball bearing. Its designed
for lots of side force so I'm sure the engineers thought one
bearing is enough.
the time when I was shopping. If I were buying another spindle
I'd definitely look at the Proxxon, but what I got works well and
no need to spend more money. I always wear ear protection when
using a machines like this. But that doesn't bother me.
bearings would be more stable. I was ready to buy the rod ends
when I learned about tapered roller bearings in car wheels.
farther apart and the length of the arm decreased then the
guidance bearings would not be required.
thrust bearings, except the tapered design also gives zero play
both axially and radialy. That's the benefit. You could still go
for triangle frame and place the tapered bearings and a far
distance. The only important thing is the two bearings must be
very parallel to each other or they will not rotate smoothly and
try to warpping the frame/mounting blocks.
bearing supplier, fairly cheap. They seem to come in industry
standard sizes, known as SET 1, SET2,...ect The bearing
dimensions are neither imperial nor metric.
normal bearings are not designed for large axial force, but for
your application the forces are not that great.
looked ok. I also drilled many 1.7mm holes and that works ok too.
The 350 mm radius of the arc seems like enough. I have a
sensitive dial indicator that I can use to measure roundout, and
side movements. I'll try to do these measurements and report the
results on my web page.
Adam.
>[cut]
>The collets on the industrial tools I've seen are all precision
> a) a good bearing. the really cheap devices only put a short shaft with a
> thread on a standard motor.
> thus only using the bearings of the motor. please make your own opinion on
> that ;-).
>
> b) PRECISION work of shaft and collars.
> the cheap grinders i have here are all no precision work.
> the bit is not centered very good, thus it will break more easily.
> the proxxon precision is fascinating.
> the collars are very strong material (hardened - very springy).
> they are ground very exactly, also the shaft is ground.
> they are shaped so that they are always centered.
> proxxon knows this, they advertise this a lot....
>
> i have inspected other tools (dremel etc) at the stores here also.
> they have even aluminium collars, far from precision..
>
ground hardened steel, exactly as you describe. I haven't
measured the round out, but its definitely not visible.
This is the standard way collets are built. Collets in the Dremal
are a cheap and nasty version. I'm just glad the store I bought
the Dremal from gave me my money back when I returned it.
I'm not sure about double bearings on the end of the motor shaft.
I think the grinder I bought has one ball bearing. Its designed
for lots of side force so I'm sure the engineers thought one
bearing is enough.
> i also think the thick throat is no help in using it (the proxxon has aYes, its oversized for the job, but that was all I could find at
> longer narrower).
> for me it looks like a chopped of angle grinder ;-).
> but sure for pcb it would be fine too.
>
>
> (the disadvantage of powerful motors (more than 100 watts) would be
> noise... you don't need much power in pcm drilling)
the time when I was shopping. If I were buying another spindle
I'd definitely look at the Proxxon, but what I got works well and
no need to spend more money. I always wear ear protection when
using a machines like this. But that doesn't bother me.
> *** 2) adams new press:Sorry, but I did some more thinking and thought that taper roller
>
> hey adam what are you doing?
> i really thought you are telling me for weeks now that a triangular arm
> would be better.
bearings would be more stable. I was ready to buy the rod ends
when I learned about tapered roller bearings in car wheels.
> i thought of placing the back bearing on the two outer edges. this shouldYes, it did. As you say, if the two thrust bearings were much
> prevent the unit
> from sideways clearance at the front.
> i thought this because your first unit needed a guidance bearing in the
> middle of the arm to stabilize.
farther apart and the length of the arm decreased then the
guidance bearings would not be required.
> it there no clearng with the new tapered bearings??yes, the tapered bearings are forced towards each other like
thrust bearings, except the tapered design also gives zero play
both axially and radialy. That's the benefit. You could still go
for triangle frame and place the tapered bearings and a far
distance. The only important thing is the two bearings must be
very parallel to each other or they will not rotate smoothly and
try to warpping the frame/mounting blocks.
> maybe i will try it anyways with the thrust bearings and triangular setup.You should be able to buy two new car wheel bearings from a
> i found two of them finally now when i searched for tapered roller bearings
> ;-).
> i had them at home all the time.....
bearing supplier, fairly cheap. They seem to come in industry
standard sizes, known as SET 1, SET2,...ect The bearing
dimensions are neither imperial nor metric.
> maybe it would get even more stable if i add two normal ball bearings onyou could do that too, but it might be complicated to build.
> the sides...
> so each direction is blocked from any slight clearance.
normal bearings are not designed for large axial force, but for
your application the forces are not that great.
> have you tested it already?During testing I drilled 50 or so 0.6mm holes and everything
> is the lenght of the arm still no problem? (difference between tangent
> movement and straight)
>
looked ok. I also drilled many 1.7mm holes and that works ok too.
The 350 mm radius of the arc seems like enough. I have a
sensitive dial indicator that I can use to measure roundout, and
side movements. I'll try to do these measurements and report the
results on my web page.
Adam.