The Right Tooling for High Output Stair and Hand Rail Production

Stair and Rail Insert Tooling

Stair and Rail Insert Tooling

Modern stair production is an evolving process. Production methods of standard, straight stairways have their challenges but typically pose no production difficulties when using the right tooling. When producing specialized curved or winding staircases, more advanced machinery and tooling is required. With the advent of 5-axis CNC machinery, this process makes these more difficult tasks much more effective.

Inser Cutter Profile

Inser Cutter Profile

 Whatever type of staircase is manufactured, GDP|GUHDO offers a wide variety of standard and custom tool choices. Beginning with the all-important machine connection, we offer standard precision collet chucks, collets and the even closer tolerance heat shrink and hydro chuck systems.  Depending on the material and construction method, tooling options can vary widely. For machining of string boards, steps and producing the required grooves and notches for the treads and risers, we offer solid carbide and replaceable insert router bits for roughing and finishing applications.

Standard Rail Sizes - Insert Cutter

Standard Rail Sizes – Insert Cutter

 For hand rail production, we again offer carbide tipped, and insert options.  Standard straight hand rails pose no production difficulties and may accept larger diameter tooling.  This application is ideal for profile insert tooling of which we offer an insert router bit designed to machine the most common profiles. This tool offers repeatability, improved tool life and due to the shear cutting angle, will produce an excellent finish quality!  Tooling for volute production requires a smaller diameter and may sometimes have to be carbide tipped as opposed to carbide insert as a result of diameter limitation.

Custom Rail Inserts Drawing

Custom Rail Inserts Drawing

Other tool offerings range from cutter heads for stringer production, fluting and carving tools for hand rails and balusters. For drilling, standard drills bits of varying diameters and lengths and custom one-step drill bits of holes with counter bores for wood plug insertion.  For answers to your questions and solutions to your problems, contact GDP|GUHDO!

Tooling Basics for CNC Machining

Below is an article GDP|GUHDO contributed to January 2015 edition (formerly FDM/Cabinetmaker) 
Understanding fundamentals of CNC tooling can make a huge difference in your costs, productivity, and efficiency.  Most CNC machining centers for wood, plastics and composite machining today are equipped with steep taper ISO/SK/BT style, or more frequently HSK style tool holders .  My favorite analogy when discussing tooling basics is the automobile (i.e. the CNC machine), the rims (the tool holders) and the tires (the cutting tool). The most well-designed car won’t go very far if it has bad rims and cheap or faulty tires. Let’s look at the importance of proper cutting tool selection and the outside factors that affect tooling choice as well as other considerations that will directly influence the machining cycle.
CNC Tool Holders - HSK 63F, RDO35 and ISO30

CNC Tool Holders – HSK 63F, RDO35 and ISO30

Start with parameters
Depending on the cutting process that needs to be accomplished, understanding the machine parameters, output, spindle, clamping and tooling options is essential. Material hold-down and dust collection setup will all play a role in the process, as will the quality, density, abrasiveness and surface finish of the material to be machined. Cutting tool selection will be predicated on the basis of understanding the foregoing properties that are already pre-determined, the expectations of anticipated feed speeds to be achieved (capacity) and cost efficiency. These all contribute in making the decision of what tooling is most suitable and cost-effective for the job.
Most CNC machining centers for wood, plastics and composite machining today are equipped with steep taper ISO/SK/BT style, or more frequently HSK style tool holders (Picture 1). The standard HSK tool holders have very high levels of accuracy, with a runout tolerance of 0.003mm (.0001”). A tool holder that is supplied with a ball bearing collet nut, rather than a single piece static nut, is preferred. The ball bearing uncouples the inner ring from the torque/threaded part of the nut (Picture 2) so the circular motion of the nut is completely converted into clamping force without any frictional loss. Advantage: more clamping force, less wear and the tool holder can be used to run both clockwise and counter-clockwise.
The most common versions of tool holders used in wood/plastics/composites utilize ER32, ER40 or RDO35 (SYOZ25) collets and their differences are shown in this chart:
Collet Style Overall Length Clamping Tolerance Max Size Diameter Available
ER32 40mm 1mm 20mm 3/4″
ER40 46mm 1mm 25mm 1″
RDO35/SYOZ25 52mm 0.15mm(premium) or 0.5mm 25mm 1″
HSK63 F tool holders, with any of the above collet types, are interchangeable between machines as long as the same “A” dimension (the dimension from top of the HSK shoulder to the bottom of the collet nut) is the same.
Specialty tool holders
While standard collet chucks are excellent clamping choices for most applications, there are heat shrink and hydro tool holder options for more specialized applications. Heat shrink tool holders are beneficial in high speed machining operations and do not use a collet system as the tool shank is mounted straight into the heat shrink chuck. A heat shrink chuck can only accommodate one size tool shank and generally requires an additional (and sometimes substantial) cost investment for heating equipment to mount and remove the tool from the chuck. It’s a great choice for carbide insert tooling, for instance, where tool and chuck are assembled at the manufacturer and won’t need to be removed for service. See Picture 3.
Another option is the hydro chuck, which also has the advantage of bypassing a collet system reducing compounded tolerances between machine and tool. Hydro chucks are balanced to 25,000 rpm and available in all common metric sizes. (10mm to 25mm). See Picture 4.
Cutting tool options
Moving on to the cutting tool options, it’s important to understand that this is the wrong place to worry about initial tool cost. Accurate cutting tool cost is measured by cost per linear foot machined. Choosing the wrong tool can severely restrict and limit the machine’s capabilities and even give back some of its selling features.
Accuracy, cost-effective production, superior finish quality, waste reduction and maintaining the integrity of machine and spindle all boil down to tool holder and cutting tool selection. Poor quality tool holders or out of balance cutting tools will end up costing far more than might initially meet the eye. Whether the choice is solid carbide spiral tools, insert tools, custom profile tooling or PCD (polycrystalline diamond) tooling, a close look at the pros and cons of each type is something well worth researching and understanding. One company can easily waste thousands of dollars if using ¾” 2-flute solid carbide compression bits to machine table tops, for instance, when a comparable 2-flute carbide insert compression bit will easily out-perform for a small fraction of the cost.
A phenolic fabricator may go through many solid carbide bits every day when a polycrystalline diamond (PCD) bit (special design for phenolic) will run considerably longer and reduce overall machining cost. Someone purchasing a carbide-tipped round-over bit to run on a CNC machine will buy a lot more bits and never maintain uniformity, when an insert tool will maintain constant diameter and hold dimensional accuracy throughout at a lower cost.
Use tools correctly
Whatever tool choice is made, the most important aspect will be using it correctly. The best cutting tool can only perform well if it is used within the parameters it was designed for. The basis of successful cutting tool performance is a synergy of machine quality/integrity, material hold-down, dust extraction, the clamping system (tool holder/collets) and tool and material composition operating under correct machining parameters.
The most important point to consider with any cutting tool is the actual chip load it will generate during the cutting cycle. If the chip load is not within the ideal range for the material being machined, it will result in either overheating of the tool and very short tool life, or, pushing the tool beyond its limits resulting in tool failure (breakage). A very prominent notion is, for instance, that more flutes on a router bit will yield a better finish. This is absolutely not the case. What leads to the best cutting results is the cutting edge moving through the material at the right speed, i.e. chip load. This single factor is probably the most responsible for tool life.
Understanding chip load
So, what is chip load? Simply put, it is the size/thickness of the chip being removed per flute/cutting edge with every revolution of the tool. So, going from a 2-flute bit to a 3-flute bit, the size of the chip is reduced by 33% if the feed rate is not adjusted accordingly. A smaller chip will increase the heat generated during the cut as the chips cannot be extracted out of the cut fast enough and are re-cut into yet smaller particles. Chip load charts found online or provided by tooling manufacturers should all be considered as a starting point/reference range only and it is up to the user to find the ultimate “sweet spot” that provides a combination of the longest tool life, finish and cost efficiency.
The chip load formula is as follows:
                  Chip Load = Feed Rate (inches per minute) / (RPM x number of flutes)
                   Chip Load = Feed Rate 600”/minute / (18,000×2 flutes) Chip Load = 0.017”
Increasing the chip size per tooth will decrease the quality of the cut, while decreasing the chip size per tooth will shorten the tool life, so it’s important to find the ideal middle where both finish and tool life are optimum.

3 flute diamond tipped bit for fast feed rates.

Cutting direction
Another consideration is whether to climb cut or conventional cut. With climb cutting, the direction of the feed is identical to the direction of the cutting edge. (As an important side note, this method of cut should never be attempted with a manual fed operation as it can result in very dangerous material kick-back). Climb cutting provides a better finish quality. When conventional cutting, on the other hand, the material is feeding against the direction of the cutting edge which exerts less cutting force on the tool and increases the tool life accordingly.
In summary, cutting tools and clamping systems play a paramount role in a CNC machining center delivering its promise of optimization, capacity, waste reduction and cost savings, as none of these promises can fully materialize without the contributions of high-quality tooling and accessories.
Karin Deutschler, president of GUHDO USA Inc., has been selling diamond tooling since its introduction in the U.S. in 1982. You can contact her and the GDP|GUHDO team at 1-800-544-8436 or
This article appeared in FDMC, January 2015. ©Copyright 2015, All Rights Reserved.

Diamond v. Carbide : Weighing the Costs and Benefits

PCD tooling Under the right conditions and with proper maintenance and handling, significant cost savings can be achieved by running polycrystalline diamond (PCD) tooling.   Understanding the basics of diamond tooling is important when contemplating its use in your own production line.  First and foremost, think of it as the marathon runner, as it will yield the best results in continuous and steady cutting of homogeneous materials.  Diamond tooling is not advisable as an all-round tool that will be required to meet demands of a wide range of cutting applications on a day to day basis.  So, if you are machining different materials and want one tool to do it all, the diamond tool will not be able to excel as well as it will if you are machining, for instance, 3/4″ MDF all day long.

Polycrystalline diamond is manufactured in a high-pressure, high-temperature laboratory process that fuses diamond particles onto a carbide substrate, which, in turn, allows the diamond to be brazed onto a tool body.  PCD has an exceptionally high wear resistance factor, in particular with abrasive composite materials that are often difficult to machine with carbide.  Examples are:  particleboard, MDF, OSB, high pressure laminate, phenolic, fibre glass etc.  Depending on what material is being machined, it is not unheard of for a diamond tool to outrun carbide by a ratio of 300 : 1!  Nevertheless, when deciding whether to switch, be conservative in your cost analysis and base your decision on the diamond bit lasting 25x longer than carbide.  You won’t be disappointed!

The original developers of synthetic diamond were GE (Specialty Materials Division) and DeBeers  (Element 6) who pioneered this process and mastered the know-how of synthesizing diamond for industrial cutting applications.  Meanwhile, there are a number of synthetic diamond tool blank manufacturers, and the quality, durability and wear resistance is not always equal.

When shopping for a PCD tool, it is important to discuss your proposed use and expectations in detail with the tool manufacturer as this allows for selection of the proper PCD grade (grain size), and optimum tool design.  In particular,  you want to be certain that there is no more PCD on the tool than actually needed (i.e. don’t order a tool with 1.1/4″ cut length when you only cut 3/4″ material because that needlessly increases the tool cost.

To understand the complete picture and compare “apples to apples” when shopping, it is important to ask the following questions:
How many times will I be able to sharpen this tool under normal wear conditions?
What will it cost to sharpen this tool?
How long will it take to turnaround a tool when sharpening?

If you neglect to get answers to these questions,  you might be in for a surprise to find you were sold a “disposable” tool that cannot be sharpened at all, or can only be sharpened once.  Or, you might think you are getting a bargain when you buy the tool, only to find you are going to be expected to pay 50% of the new tool cost to get it sharpened.

These factors significantly affect the cost per linear foot machined so are important to know when doing a cost comparison or justification for PCD tooling.  Below is an example of a cost comparison using a diamond saw blade versus a carbide tipped blade:

Screen shot 2012-12-04 at 11.59.11 AMcost per linear foot formulaScreen shot 2012-12-04 at 1.01.11 PM

$.0028/$.0143 = PCD costs 19.6% of carbide when comparing $/Linear Foot (80.4% cost reduction) 

Another advantage of PCD tooling, apart from the longer tool life,  includes the quality of finish which is often significantly improved and therefore requires less sanding.  With carbide tools, the finish starts to deteriorate from the very first cut onward, whereas the diamond tool maintains a nice clean finish right up until it becomes dull… which time it plummets and should be pulled for sharpening.  Pushing a diamond tool to run a little longer once it shows signs of becoming dull  (a good indicator is when the machine amps increase), can result in a substantially larger sharpening cost as the diamond face can shatter and require re-tipping/replacing of the cutting edge.

At first glance PCD tooling seems expensive when compared to carbide however when we compute the cost per linear foot machined, in the right application, PCD will be revealed as the only choice for discerning shops that are cost conscious.  As you can see from the cost calculation above, the investment in PCD tools pays off rather quickly. Some of the top PCD applications are machining abrasive materials, composites and workflows that do high volume of the same cut and material type.

With PCD router bits, maintaining correct chip load is very important as heat buildup during the cut will damage the diamond and can lead to tool failure.  Accurate tool clamping systems with close tolerances are also essential as is firm material hold down to avoid any vibration during the cut.   For specific questions about PCD tooling, please contact us or give us a call at 1-800-544-8436

Tooling for Cutting Composites

The use of composite materials has been on the rise for years due to their unique characteristics including reductions in weight and increased flexibility.  By definition a composite is a combination of two other materials used to create a unique material that is superior to either input material (a super-material?).  The performance increase makes composites more difficult to machine,  however, selecting the proper tool for the application is paramount to optimizing tool performance.  Each composite type comes a unique set of cutting challenges due to the materials structure which, unlike metal or wood,  is composed of layers of fibers and resins bonded together with intense heat and/or pressure.

ceramic fibersDue to structural differences, composites will behave differently based on the materials used in the creation of the composite, so when cutting a new material it’s important to do a test cut on scrap material.   Cutting composites requires getting through the different layers of various material types by chipping, ripping or shredding.  Common composites include carbon fiber or fiberglass layered and bonded by polymer resins such as epoxy and polyurethane. Each of these layers react differently when cut and the heat generated by the cutting tool can cause de-lamination or worse if not machined properly, leading to excessive tool wear and a change in tool geometry.

Diamond tipped (PCD) tools are often most effective in cutting composites as it’s important for the tool to cut with minimal force applied to the material. Composites will “eat” through solid carbide tools in many cases, so while the sticker shock of PCD may detour some people the cost per linear foot machined will be drastically decreased when compared with solid carbide.

With drilling composites, splintering can be an issue, so using PCD tools is especially important as a dull bit will lead to layers being pushed aside vs being cut.   This leads to de-lamination or “blow-out” on the exit side of the material.  With a new material it’s best to test the characteristics prior to machining any large project as the observable properties will be important in finding the right RPM/feed rate to optimize cut quality.

Screen Shot 2013-08-17 at 7.22.28 PM

Carbon Composite/ Fiberglass Reinforced Plastic Example

The example carbon fiber tools used:

1 Diamond-Dowel Drill

2 DIATEC-4 Diamond Router Cutter

3 DIATEC Diamond Cutter w/ Alternate Shear Angle

4 DIATEC-4-Quattor Diamond Router Cutter

 For more information on application specific composite tooling contact us today so we can discuss your exact needs.