Modifying a Moulder to Run a Deep Profile

Trying to push a moulder to perform outside the limits of its original design can result in serious injury. January 29, 2009

I run a Bridgewood 757 moulder. I have a very deep profile to run. The only way I can see doing this is to grind away a lot of chipbreaker and pressure foot to allow for the swing of the cutterhead. Wise? Safe?

Forum Responses
(Forum Responses)
From David Rankin, forum technical advisor:
First of all, check the maximum cutting circle that the machine manufacturer has specified. There have been many cases with different brands where the specs could not be met. If this is the case, go back to the manufacturer and ask their direction. If you are trying to exceed the max cutting circle, you may be responsible for any injury that results.

As a general statement, it is common to use different pressure shoes and chipbreakers to run different profiles. If it is necessary to make minor modifications of the pressure shoe or chip breaker shoes (not the chip breaker itself), do so with the understanding that you must stay within the manufacturer's specs.

Also, if you are running a deep profile, the knife projection should not exceed 3 times the thickness of the knife steel. Example: 1/4" thick steel can run a 3/4" depth of profile max.

From contributor J:
Dave has good points to consider. The other is horsepower. Got enough? I say if it all looks good, go for it. I'm not familiar with your moulder, but the one I run, over the years has pulled some tricky stuff off (safely). Made wooden parts to carve into, bought plastic parts for the same (fences, chip breaker, pressure shoe). Just make sure the wood is held down and the cutter can swing free. Feed slow and have fun! Just keep thinking through the whole setup... safety, safety, safety.

From contributor A:
If the Bbridgewood 757 moulder is the W&Hussey clone, then it is possible. We have run rather deep mouldings on a W&H for years by doing exactly what you mentioned, i.e. grinding away a bit of the casting for more clearance. Most of the W&H knives are cut out of 1/4" stock.

Dr. Rankin essentially was referring to break strength of the cutter while doing deep cuts. Our grinding company always used 5/16" steel for all of its W&H cutters. We have always felt safe. Something else on the machine will break before the 5/16" cutter. I think we've cut at least 1" deep for large crowns. Maybe deeper. The machine is rated for 3/4".

From David Rankin, forum technical advisor:
For clarification, the Bridgewood 757 is either a 4 or 5 head moulder. The Williams and Hussey is a single head machine. With both machines there is a depth limit. Many profiles require that the depth limit is exceeded. It is always recommended that you do not exceed this limit. You may do so for years without a problem, but when you do have a problem and have exceeded the machine's specifications, you have assumed machine liability. As an expert witness for such cases, I have to strongly recommend that you do not exceed the machine limits. I am not trying to be harsh, just trying to be safe.

From the original questioner:
Thanks for all the responses. My tooling provider suggested doing part of the profile with the outside cutter, allowing me to get back to the 3/4" max of the top head. Side knives are being made now.

From contributor R:
People, please listen to Dr Dave's advice! I have witnessed people who have exceeded the machine's limits, and it's not pretty. The machines have limits so you don't get killed doing foolish crap. If it is not capable of doing within the machine limits, don't do it!

There will be many people here telling you about all the stuff they do, but they are miles away from you and won't be there when you get injured. They also won't be there when you're in the hospital, physical therapy, OSHA investigation or the courtroom. Listen to the doctor, or you will visit with one real soon.

From contributor J:
I don't think anyone here was suggesting an unsafe setup. We all respect the wisdom of you all. The questioner has been around for a long time and I believe he knows right from wrong. Your concern is worthy, as well as Dave's, and should be followed to the tee. Because we offer past experiences of our jobs and things we have done does not make us bad influences to anyone we are trying to help. Just trying to share a similar experience and help someone out.

From contributor R:
I have been in over 1000 shops in this industry and shaken the hand of at least 100 people with fingers missing - some even one hand missing - from industrial accidents. Most will tell you they did something they should not have done. If you are insulted by my comments, my apologies. But when people comment about machines that are not even the same machine types and then tell them to grind away the casting, all I can picture is an accident waiting to happen. Chip breakers can be moved or replaced with smaller ones, but grinding away the casting of a machine is raising a big red flag, probably filled with the victim's blood.

Come on - know what machine the poster is asking about before you post unsafe comments. If you have modified the manufacturer's machines and gotten away without getting injured, good for you. Consider yourself lucky, but don't post your unsafe practices here. I have seen the months and years these people suffer through their injuries. I also testified in a case where the victim lost his whole hand because they modified the machine.

From contributor R:
It is the responsibility of the operator to know the limits of the machine he or she uses. Every manufacturer lists the max cutting circle for the machine in the owner's manual. Most manufacturers have a line in the gib area on the side of the cutterhead to show the max knife projection. If you don't have a manual, call the manufacturer.

As a moulding designer and tool maker I always ask what type of machine and what the max cutting circle of their machine is. I have turned away customers because they wanted tooling made that exceeds those limits. I do not use 1/4" thick steel because of its safety limits.

In my opinion the manufacturers have done their part in trying to make machines that are safe to use. I have done my part to make tooling that is safe.

In this case I applaud contributor J and his tooling manufacturer for coming up with a solution that is safe.

From contributor O:
I have found that in most cases you can convert any really deep cut into several shallow ones. There is of course more cost in steel associated with the cheaper one knife plow scenario, but the risk far outweighs the cost.

I have also found that if you need to cut into a chipbreaker, or shoe, for maximum control, you can easily get one milled up for you at any machine shop, out of Delron (a heavy, super wear resistant plastic, cheap). The knife will cut through this like butter if it gets raised up somehow, but it will hold the piece down as well as a solid shoe (for a while anyways, until it gets badly worn.)

From the original questioner:
Thanks! I actually had some of this Delron at my facility. Machined it out myself to work as a chipbreaker shoe. Results... Great! Took my time on the setup.