Hitting The Target With Pictures by PC
This is why RINK FORMGRIFFE has, since their founding in 1995, manufactured close on 40,000 customised anatomical grips for air, sport and free pistols, delivered to amateur and professional marksmen such as Olympic champions Christian Reitz (Deutschland) and Jong Oh Jin (South Korea), in over 100 countries worldwid.
Thomas Rink (company founder and owner - Figure 1) owes his expertise to his long-standing membership in the German national shooting team and the Army sports group of the Bundeswehr. His shooting successes include fifteen German championship titles. Rink subsequently trained as a wood working technician, with his final thesis being “Manufacture of custom-made handles for sports pistols using CNC technology”. This initiated the founding of RINK FORMGRIFFE and a close on 30-year partnership with German CAD/CAM software developer SCHOTT SYSTEME GmbH.
Much of the company’s success is built on providing one-off tailor-made pistol grips and stocks for professional marksmen (in addition to a range of standard grips and stocks). Such is the demand that Mr. Rink comments “We are particularly proud of the individually tailored grips for which our customers come to us from all over the world and accept waiting times of 6 months”.
An extensive selection of pistol types from well-known manufacturers such as Feinwerkbau, Pardini, Steyr and Walther have all been modelled using their Pictures by PC CAD/CAM software from SCHOTT SYSTEME. These CAD models provide the pistols mounting areas that need to be milled from inside the grip so that it perfectly marries to the customer’s pistol, with Rink commenting “So far, we have used the CAD functions to design the various gun models and we have around 100 in our program”.
Although customers can provide Rink with approximate hand dimensions online for their pistol grips, a fully customised service is offered directly at their workshops in Ehringshausen, Germany. This process involves wrapping a silicon modelling compound around a grip blank and imprinting the customer’s hand directly in the silicon (Figure 2). Rink elaborates “The aim of the silicone model is to ensure that the shooter can hold the weapon in a relaxed manner and, above all, consistently. This is best achieved when the grip fully fills the hand and the wrist does not have to be twisted unnaturally.”
Where Craftsmanship and Technology Combine
When reverse engineering the silicon grip into a 3D CAD model, areas of special importance are, for example, the sharp edges that form the ridges for the hand and finger imprints. As these areas in the formed silicon can be very uneven, a full 3D optical scan will also result in uneven mesh models, making accurate 3D CAD modelling difficult. Instead, Rink uses a Microscribe stylus to digitise just a few hand-drawn curves at strategic positions, such as the edges, on the silicon (Figure 3). Then using SCHOTT SYSTEME’s open programming environment, Rink has created procedures to automate a number of processes for generating the 3D CAD model. These include interfacing directly with the Microscribe stylus, as well as importing the 3D digitised polygons and automatically smoothing these into 3D Bezier curves to form the basis of the 3D surface grip models.
SCHOTT SYSTEME’s 3D hybrid (Solid, Surface, Mesh) CAD modelling tools then enable the addition of finishing touches to the grip form. These individual changes can be performed on solid, surface and mesh models and include deforming the surfaces (bumping), changing dimensional sizes (offsetting, scaling) as well as bending the grip (global shaping). On these hybrid modelling capabilities, Rink comments “Without Pictures by PC, the complex tasks would not be possible. Of course, I also had other programs in mind, but none were as open and flexible as PbPc.”
When 3D Printing Is Not Always an Option
In a world where 3D printing is for many increasingly in focus, Rink remains with more traditional manufacturing methods, explaining “Various manufacturers have already tried 3D printing, but the feel of a real wooden handle cannot be achieved.”. Even with the development of 3D printing materials, he elaborates “Even so-called wood filament does not offer the sweat absorption capacity of solid wood.” – a factor which is a vital requirement of the grip as any slippage while holding the pistol ultimately effects shooting accuracy.
The company therefore continues to rely on their three ISEL 3 axis CNC machines coupled with their Pictures by PC CAD/CAM software, both purchased back in 1995. The complete process from digitisation to milling data takes approximately 30 minutes, with the creation of the actual CAM toolpaths only taking 5 minutes. Herr Rink comments “With the many different milling technologies offered by the CAM module, we can perfectly program both the very complex 2.5D internal features and 3D external milling operations.” The machining of the left, right and internal components that make up a completed grip requires approximately 1 hour in total, with the customer choosing from either Walnut or coloured plywood made from Finnish birch.
With the aforementioned dispersal of hand sweat still in focus, the last manufacturing process is the stippling (mechanical roughing) of the skin contact surfaces on the grip. This results in a larger surface so that the sweat can be absorbed and released again more quickly. Additional fine handwork of grinding and polishing is also required to produce the championship winning grips and stocks (Figure 4).
A Championship Winning Team
With close on a 30-year working partnership between RINK FORMGRIFFE and SCHOTT SYSTEME GmbH, Mr. Rink comments “Over the years, SCHOTT SYSTEME has always helped us to implement our requirements very quickly and easily. That's also a main reason why we haven't even thought about changing since the DOS days (Pictures by PC Version 2.6).” The 40-year product continuity that Pictures by PC offers (across all DOS and Windows platforms) has also enabled the company to update to the latest 3.10 version while still being able to seamlessly use all of their 30-year legacy CAD/CAM data. Finally commenting on the software support Rink mentions “The support at SCHOTT SYSTEME is a dream: no additional costs and yet a competent answer or solution within a day at the latest!”