Tech Talk
What Should I Know Before Ordering a "Custom Tool"?
How many times have you ordered a Custom Cutting Tool and not received what you were expecting? Or, the tool looks just like the what you thought you were getting, but it won't do the job?
It's a pretty safe bet that most regular buyers of custom profiling tools have had at least one experience with a tool order that went sour. Often this results in everyone involved pointing the finger of responsibility at someone else, and usually the problem is a simple lack of understanding between the tool representative and the end user, as to what was being made. It may be a perfectly good tool that has been properly designed, but because of a lack of clarification as to exactly what the tool was intended to do, or the performance that was expected from it, the results are less than satisfactory.As manufacturers of custom tooling it is our responsibility to make sure the customer knows exactly he is getting, and what he can expect from it, before we start building it.On the surface it looks quite simple -"Here's the profile I want, and here's the machine I'm going to run it on..." - but as anyone who has learned the hard way knows, there is a bit more to it. There is about a dozen design decisions that have to be made by the tool maker, and probably twice as many application details, that have to be clear, before those design decisions can be made. And, both the user and the toolmaker have to know the application specifications, because any assumptions, according to that clairvoyant Philosopher Murphy, will be wrong.The first specification, of course, is the type of tool. This may seem ridiculously obvious, but often a customer will have in mind that he wants a custom made shaper head and closes his thinking to just that, when in fact, an experienced tool salesman will realize that it would make much more sense to run this job on his router, for example.The actual profile of the tool is, obviously very important, and there are always details of the profile that have to be discussed. Such things as; how critical is the shape; does it interlock with another tool; does it have to match a sanding head; or does it have to match an existing tool? Do you want the radius to flare off, or do you want it to stop at a certain spot? Do you want the profile extended because the material may vary? Is the tool going to do more than one job, ie; you can design a set of tools to both corner round and bullnose, or corner round and bead, but not if this is not made clear in the beginning.Make sure you are clear on what material you are going to cut, and if there is going to be more than one material. The thinking that if you design the tool for the toughest material you have it will easily cut the softest, is wrong. Even though a sharp tool will, assuredly cut almost any material, there is no cutting edge that will cut everything efficiently, and by specifying your range of material you may have to make a decision on which is more important. This also ties in with the quality of cut. If you don't require a high quality finish, a tool could be designed that is less expensive, more versatile, and will cut faster. But, if finish is critical, it is very important that the designer knows it.In the case of machining solid woods, make sure you specify if it is cutting across the grain, down the grain, or both. If it is a composite material - is there a finished surface, such as Melamine, HPL, or veneer, etc., and is it on one, or both sides?In most wood machining applications, the cutting direction, or rotation, is against the direction the wood is fed into the tool, or the tool is fed into the wood. However, there are operations that have the tool rotating in the same direction as the as the feed. If this climb cutting action is not taken into consideration it could seriously affect the tool's performance.Chip load has to be calculated for optimum tool performance. The information needed from the user, is the spindle speed and the feed rate. This coupled with the tool diameter and an estimate of the amount of material to be removed will help in determining the correct number of cutting edges.Depending on the job, there may be a difference in how the tool is designed, based on whether the machine is automatic or manual feed, so make sure this is added to the list of vital information.On vertical spindle machines you have to decide if the widest diameter portion of the tool is going to be on the top or the bottom. You may have a personal preference, but in some cases the material and the profile may be the determining factors, and what you prefer may not be the most efficient or practical way. This should be part of the discussion with your tooling representative.Tool diameter was already mentioned, but don't forget to consider things such as guards, fence positions, collars, bearings, dust hoods, and, of course, safety, when calculating the size of the tool.When the tool is to be installed on a multi-spindle machine, which spindle the tool will run on is very important, and if not specified, could result in the tool being made backwards and virtually useless.In addition to all of this, there are a lot of little details that should be cleared up. If it is a router - do you expect it to be able to plunge into the wood? And, in CNC routing applications you sometimes have to consider hold down. On one occassion that I recall we were given the profile but not a drawing of the finished part and the user didn't realize that it was so small he was going to have problems holding it during machining. By modifying the tool and changing the procedure we were able to solve the problem, but it all could have been avoided if we'd known. In a stacked or expandable tool do you want the tools locked? Are you expecting a selection of spacers for various wood thickness' and to compensate for tool wear, and, how much is the range of expansion you want built in? If it is a spindle tool- are there any keyways or drive pins?If you are expecting accuracy, make sure a dimensioned drawing is produced by you or the tool supplier, plus a sample of the finished product, when available, can be a big help and may answer a lot of the manufacturers questions.Finally, if you have a tool that is doing the same, or a similar job, and it works really well or not as well as you would like, bring this up. It might help clarify what you expect and eliminate some design decisions. Also, if there is any peculiarity in your machine or set-up that may affect the tool, advise the tool representative. There may be something that can be done to compensate.Now that all this pertinent data has been downloaded to the grey matter of your tool representative; what should you expect? -- Stay tuned... by: Doug Reid, President, B.C. Saw
