If you do not find the answer
to your question below, try our Reference
Library or write to
support@PreciseBits.com
Can
I use solid carbide end mills on any machine?
I
am new to CNC. what do you recommend?
What should I know about routers?
Can I
use a Dremel® or compatible device with PreciseBits tools?
Can I use a
RotoZip® Rebel on my CNC router?
Carbide grade have improved substantially during
that past decade. Higher transverse rupture strengths, more resistance to
shattering and a greater understanding of the role of each chemical component in
the mix have resulted in the introduction of solid carbide tools in applications
that once demanded high speed steel with exotic surface treatments. Nonetheless,
the stability of your machine and the way your have it set up are very
important. Consider the following items (in order of importance):
- Spindle Runout (TIR) - should be less than or
equal to 2% of the tool's diameter (absolute maximum).
- Spindle axis to table orthogonality- should be
at 90° with no more than .1° variance.
- Spindle Peak RPM - most of our tools
require a minimum of 15,000 RPM under maximum
anticipated load.
- Collet Retention Force - the collet must not
let the largest diameter tool you will use slip under maximum
anticipated load.
- Appropriate Feed Rates - motor drivers should
be capable of moving the bit (or the workpiece) fast enough to prevent
burning and tool overheating.
- 0 (Zero) Slip - 0 (Zero) backlash in x
and y axes.
- Proper hold down of work piece.
The above notwithstanding, a number of VERY
skilled cuemakers successfully use our 0.010" tools on manual pantographs
operating at 8,000 - 12,000 RPM. From their experience it is apparent
that even our smallest diameter cutters are compatible with manual equipment
if the the skill of the operator is sufficiently high.
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Talk about a question that needs a entire book
to answer. In lieu of a complete, useful answer, we can only offer a
few pearls of advice.
First. Go slowly. Give yourself time to
learn the equipment and to become familiar with the vagaries of cutting wood
before investing a lot of money in precision tools. Start with cutting a
reasonably uniform wood like maple. It doesn't cost much, cuts
beautifully and can be used to test every aspect of most CNC systems. Start with larger sized
bits (0.0469" and above).
They are cheaper and harder to break than the smaller bits. Once you
get the hang of it (count on a month or so) get some smaller bits as
needed. Some of our 1/32 in. bits are relatively cheap and are a popular
size for new CNC users.
Second. Take time to understand how the parameters that you set with your
controller configuration affect bit life, cutting time and overall system
performance. There are subtleties (like feeds, speed and acceleration
ramps) that you need to master in order to be effective with your new
equipment.
Third. Take time to talk to the vendor that you
anticipate buying your machine from. If they do not have time to help
educate you now, it is unlikely that they will be very helpful after you have
left you money with them. Shop around. There is a lot of new equipment
out there, some of it very good, some of it not so good. Price is
definitely not the final determinant of quality. A number of modestly
priced systems appear to work as well as much more expensive equipment. The
most important issue is to size the system to your needs. If you are
going to be making pool cues, you do not need a US$50,000 CNC router with an 8
HP Colombo router and a 4' X 10' X 1' machining envelope.
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Compact CNC systems are often
mounted with a low-cost shop router instead of a more expensive variable speed
spindle. In spite of being quite noisy, a router can give years of
reliable service in operations requiring modest cutting power and minimal speed
control. There are two types of
routers commonly in use on CNC machines: plunge
routers and laminate trimmers. Plunge routers are designed for continuous use
and are equipped with adequate cooling to prevent excessive heat build up.
The shafts are typically mounted in high-quality, sealed ball (or roller)
bearings and backed up with a thrust bearing to allow drilling and ramp milling.
Typical units cost between US$90 and US$350. Laminate trimmers are much
more compact and generally much cheaper (US$45 to US$100). They are
intended for intermittent duty, but, with light loading, can provide reasonable
service in a CNC environment.
Spindle
speed (RPM) is very important when you are cutting with microtools. If
you are fitting a shop router to your CNC, we recommend that you use a
variable speed plunge-style router. Plunge routers typically operate in
the 25,000 to 30,000 RPM range, as opposed to 18,000 to 22,000 RPM for the
single speed laminate trimmers. More importantly, they are usually built
around a so-called universal AC/DC motors that, with external controllers, can
be operated from a few hundred RPM up to 120% of the rated maximum. One
disadvantage of plunge routers is that most of them vent all of the cooling
air through the bottom. Unless you redirect this blast of air, it will
render any vacuum removal of debris totally useless and your shop will slowly
be buried in sawdust.
No matter what type of router
that you decide on, go out an buy a dial test indicator with
0.0001" (0.0025 mm) resolution. You will use this gage to
periodically measure the runout of your "spindle" to determine when
the bearings need to be replaced. Excessive spindle runout caused by worn out
shaft bearings or a damaged collet adapter is one of the major causes of breakage
with small rotary cutters. PreciseBits currently offers precision
collet adapters for a limited number of low-cost router / laminate
trimmers.
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Are you using a Dremel mounted on a CNC stage or
intending to use it by hand?
If the unit will be mounted to a CNC system you can use any of our tools up
to a 1/16" (0.0625", 1.59 mm) cutting diameter. Larger diameter
cutters will put too much of a load on the Dremel leading to overheating and eventual
failure.
If the Dremel will not be mounted to a CNC
system, highly recommend the use of one of their attachments: cutting kits, router
attachment, shaper/router table or a drill press attachment. If you will be
using the tool by hand, stick to the larger tools (0.0625" to 0.1250",
1.59 mm to 3.18 mm) to minimize breakage.
CAUTION: We have measured a
number of Dremel grinders and have yet to find a unit with less than 0.006 in. (
0.15mm) TIR. If you plan to use bits smaller than 0.0469 in. (1.20mm) you
will need to replace the collet adapter with a more precise component.
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I just recently purchased a CNC machine which
utilizes a Rotozip Rebel. I'm going for the smallest diameter cut possible
for very fine cutting/engraving into oak. The Rotozip tool utilizes 1/4
and 1/8 bits. Could any of the bits on the PreciseBits site be utilized for
the Rotozip?
The challenge with the Rotozip is that the runout
(TIR) of the spindle increases rather rapidly with wear. We are not
familiar with the Rebel model so the problem may have been fixed. In any
case, if you are new to CNC woodworking, start with relatively large, robust
cutters (0.0469" and above) to gain experience and to get a feel for the
material that you are cutting. After you have made some sawdust and feel
adventurous, move on to more detail oriented tools (0.03125" and below).
You will find that clear maple (a medium density hardwood) cuts beautifully, with
little fraying, accurate sidewalls, and no splintering to speak of. Assuming
that your CNC is up to the task, tolerances of +/-0.002" are routinely
achievable.
No matter what type of
spindle or router that you are using, go out an buy a dial test indicator with
0.0001" (0.0025 mm) resolution. You will use this gage to
periodically measure the runout of your "spindle" to determine when
the bearings need to be replaced. Excessive spindle runout caused by worn out
shaft bearings is one of the major causes of breakage in small rotary cutters.
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