Spoil board material - discussion

A word to the wise, Bill. MDF is just dust and glue. Unfortunately the bonding of MDF uses Formaldehyde in the process and this is a known carcinogen. Some countries have banned its use but if you are machining it, it is better to wear an effective FFP3 mask.

Preventing the particulates, which tend to stay in the upper respiratory tract can be done with any mask that can filter large particulates. Preventing the chemical attrition requires an FFP3 type of mask. I now don’t cut MDF, which is usually everyone’s first and cheapest carving material. It does not hold detail and it is not a good test material.

Ultimately, using MDF as a spoilboard is common but unnecessary. Better solutions which require a little investment in time, money and fixation solutions are readily available. MDF, where unfinished can also leach chemicals in the medium term.

Thank you for this very helpful feedback. I prefer not to use MDF as well - but can you recommend a good alternative? Thank you very much-Bill

I guess it depends on many factors, Bill. Cutting a very long story short, I would say go straight to an aluminium sea of threaded holes with modular vices. I have not regretted the purchase though in the USA, I believe they would call it ‘spendy’. It would be known as expensive elsewhere.

I have followed all of the initial work practices using the MDF baseboard (as supplied with the machine) with an MDF spoilboard on top because I liked the idea behind resurfacing. I have used a variety of stainless dowels from the underneath. The MDF was 18mm (3/4") and the baseboard was the same thickness. It was easy to mark it and drill it for six 10mm diameter dowels that were sunk by 5mm, leaving 5mm proud to inset into the underside of my easily removed spoilboard. The total loss of Z height distance amount to 36mm.

Clamping became a more urgent requirement so I inserted several rows of M6 threaded inserts from underneath to a depth of 10mm, leaving me an 8mm depth of spoilboard to resurface. Unfortunately, the constant tightening and loosening of the clamps resulted in me experiencing inaccurate work-holding. I had found that workpieces were increasingly shifting sideways slightly under pressure of the cutter engagement.

Having spent a lot of cash on solutions that still would not let me cut metal, I looked elsewhere. Locally, I could find engineering companies that could manufacture a sea of holes for me but the costs were really prohibitive. I looked at cutting my losses and buying a different but quite expensive machine. Eventually, I discovered Saunders Machine Works and they had made stuff for my machine as a stock item.

I purchased the 12mm (1/2") aluminium fixture tooling plate with 840 M6 holes, the three stiffener rails and two modular vice sets along with the standard and some additional Mitee Bite jaws. This has improved my work-holding opportunities by providing an infinitely variable means to hold the workpieces. I am no longer concerned with resurfacing a spoilboard because I do not use one.

Coming back to the dependent factors, we will all have different requirements. Mine are to use the CNC machine for a hobby and to carve/mill anything I want to with the greatest of ease and the highest level of accuracy which my machine can deliver. The rigid baseboard created a far more rigid machine that improved everything I did. I can see that this type of solution (fixture tooling plate) is not for every one.

I believe all of the hobby CNC machine manufacturers should move away from MDF. It is not rigid, it loosens with use and it leads to the hobbyist using poor methods of work fixation. It needlessly creates an MDF environment as well and this can potentially damage the user. To some extent we can ameliorate the effects of MDF by wearing an effective FPP3 mask. In the final analysis, I had wanted to achieve much better accuracy so that I could cut metal. I realised that my hobby class CNC machine could deliver it with a more conventional approach to work-holding and machine rigidity.

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Hi Bill. Further to the discussion above, I thought I would add a couple of images to illustrate the general direction of my thoughts.

Holding the stock workpiece so that it stays where it is has been put is the primary reason for considering how we hold the workpiece. Another part of that requirement is to hold the piece firmly so that when it is engaged by the cutter, that the forces generated to remove material from the stock do not shift the workpiece out of position. Subsidiary considerations will be acceptably smooth finish, tool life preservation, machine rigidity and working tolerances.

The image below shows three sided work holding while milling a 6.35mm (1/4") slot to remove a 20mm (0.787") thickness of stock at a 60° angle. The wood is Cedar. Please Note: I do not routinely recommend three sided holding for milling, especially when undertaking slotting operations, but you can see that this was an effective strategy. The modular vice half at the bottom of the image is a movable vice and it was used merely as an end-stop.

The vice on the right of the image is also a moveable vice that can move roughly a centimetre when the bolts are loosened. The vice on the left of the image is a fixed vice and the image shows how it differs from the moveable vice. The vice on the left is fixed into its position by two M6 countersunk bolts. The vice on the right is held in place by two cap head bolts. When the bolts on the vice on the left are loosened by half turn of each countersunk bolt, the vice can be moved about a millimetre. I use a technique that loosens the fixed vice by one millimetre and then I push the movable vice against the workpiece (which pushes against the fixed vice) .

I tighten the movable vice in position and then tighten the fixed vice in position. The countersunk heads of the bolts serve as an impromptu vice centering mechanism and pull the fixed vice tight up against the workpiece. The serrated jaws of the vices are 5mm (0.196") deep and the workpiece rests on a 1mm (0.039") wide ledge. The workpiece is held firmly. I always tighten the bolts using a torque wrench set to 5 Nm. This preserves the threads in the baseboard by applying a light, consistent torque to the bolts.

The following image shows a simple clamp setup. There are eight clamps used even though less would hold the workpiece for laser engraving but this was set so that two pair of clamps were never undone. I had quite a few of these pieces to engrave with different images and this was my method of ensuring all of the images were central on the workpiece. The workpieces were changed after each was successfully engraved. The clamping surfaces were fixed below the level of the workpiece so that the laser could pass over them without damage. My laser operates at a distance of 3.175mm (1/8") from the workpiece so not hitting clamps is always a consideration.

The arrangement of threaded holes permits me to do other jobs in the middle of any particular task and then come back to a job and know that clamps or vices will be set into the positions that they were in previously. My growth in CNC work has seen many different types of operation. These have been supported by being able to hold the workpieces in any number of variable configurations; which are reproducible, stable and rigid.

I hope this is useful information.

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All info is useful! That’s a fancy chicken :slight_smile:


Good to know @RickW. The chicken is from the family, Corvidae. I don’t see KFC or the Golden Arches cooking and selling them anytime soon. :joy:

@jepho really cool art! I don’t eat chicken no matter where it comes from…

Crows are considered to be pests in the UK but I don’t know if anyone has eaten them yet. The recent re-classifications for game birds in the UK included Crows and Magpies so they can legally be shot. If I can find a friendly farmer who needs a few pest birds discouraging, I may be able to get a permission to shoot on their land. I have a shotgun which needs a little more exercise.

Yep, crows are a pain and they steal bones from the Rotties. They really don’t like those birds so I couldn’t get a shot off in time. They only got 3 so far, 10 rabbits and one squirrel. Very good art!

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Formaldehyde has not been used as much in a long time. However there are alternative MDF products that have no harmful glues or products in it. So please do not throw around that statement without knowing all the facts. At least give the whole truth of the situation.

I would be most interested to learn about your own version of the whole truth… meanwhile, I have assembled a few different sources for my position.

Formaldehyde is present in many wood products because it is a naturally occurring substance. MDF is a known risk because of its manufacturing process and formaldehyde is considered to be carcinogenic in the UK and the EU.

My first link is somewhat confused but nevertheless, it portrays the issues reasonably well.

The second link is to the USA Centre for Disease Control which is considered to be an excellent source for reference. Their research paper was published in 2019.

My third link is from a British broadsheet newspaper that is considered to be a reasonably well-researched newspaper with journalistic integrity.

The fourth link is quite specific about many types of chemical, even referring to the natural occurrence of formaldehyde in wood.

The last link is to the Health and Safety Executive of the UK. A government body which can be considered analogous to OSHA in the USA. The advice they give is considered up to date and will protect workers and employers.


So use a dust mask with a decent dust extraction set up. Stop being such an alarmist there are ways to mitigate the dangers from the least of all is the dust and other things in the products we all use on the cnc.

I provided some information to another user. They may not have been previously aware of that information. You made the point that I was not being entirely truthful. I provided the evidence for my current position. The evidence does not support the notion that I was not being truthful. Your ascription of the epithet “Alarmist” to me is neither accurate nor justified, given the context.

It should be possible to discuss the validity of an argument without attacking the proponent. You disagree with my stated position and continue to attack me. Many of the people who use this forum are new to the world of CNC machining. Providing information that is based upon personal opinion is unhelpful. Argue your position without making personal attacks.

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I’ve got to be honest here, but you’re being quite dismissive of the facts. One of the fundamentals of tradecraft is health and safety, specifically yours and anyone else you may affect in the course of your endeavours. To be so dismissive is tantamount to neglect - and there are too many people suffering from respiratory diseases and conditions that may have been preventable with the use of an appropriate level of protection.

Your lungs, like your eyes, are precious. Protect them at all costs!

I am a health and safety officer in Ontario and I know the dangers of the elements and chemicals of the products your talking about. The fact of the matter is that proper PPE and dust control in a shop and around a cnc machine can and will eliminate most of the danger you are talking about. So Throwing this information out there is good . I am not making any personal attacks on anyone I felt you were in your response to me. You figure I don’t know squat. I however do know what is needed to protect myself under these conditions. So maybe some face masks and dust collection no matter what wood since any wood fiber can cause an allergic reaction or lung irritant. is a good idea. Also a set of good Eye protection glasses or face mask to protect for flying debris and hearing protection is a good idea.

When ever I see someone post a mountain of scientific information on a subject like this as you have I think Hmm. His point is lost because most wont ever read it. I did not. I know the dangers. But you dismissed everything I said because you took it the wrong way. Yes I realize I could have put it across better. The fact is there are greener alternatives out there. Ones that do not use those chemicals. Do a google search you will find them. You good at doing that. Yes the US banned formaldehyde not MDF there are alternatives to it in the US.

That site you posted was a PDF not an actual site so where is the statement from the US government saying they Banned it?

Like I said there are alternatives. We can stop with the rhetoric.

I’m not at all sure that entering into this discussion is a good move on my part. That said, here I am.

I was fascinated by the links the Greg posted to rice straw based MDF, so I made some calls this morning. Unfortunately, what I learned was not positive. Columbia Forest Products, which is a major manufacturer of MDF in North America, is the company named in the online article as being a Canadian supplier of the rice-based product. I called the head office of Columbia, and I was told that, unfortunately, the deal never came about. The man that I spoke to said that he believes that there is a small amount of the product being manufactured, but the financials never resulted in large production and exporting to Canada.

I am not posting this to contradict anything in this thread so far, merely to point out that it would seem that the industry in North America is a long way from producing a true formaldehyde free MDF, so we need to “be careful out there.”

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The third subheading heading you did not read in the first linked item had stated verbatim:
(It turns out that MDF isn’t banned;)

Question 6 in the Health and Safety Executive, 5th linked document from the organisation charged with overseeing health and safety practices in the UK specifically asks verbatim: (Is MDF banned in other countries and, if so, why not in the UK?)

You did not read the first linked item and you have assumed what must have followed. You did not read the paper published under the CDC auspices and missed the fact it was a highly technical and erudite research paper entitled: POSSIBLE HEALTH IMPLICATIONS FROM EXPOSURE TO FORMALDEHYDE EMITTED FROM LAMINATE FLOORING SAMPLES TESTED BY THE CONSUMER PRODUCT SAFETY COMMISSION
dated 22nd March 2016.

Given your occupation; I would have expected you to read it… or at the very least to cross reference it with similar research held by the Canadian Centre for Occupational Health and Safety (CCOHS).

I did not doubt that. My point was made to a person who had not stated that they were a health and safety officer. I believe I know the dangers inherent in using MDF but that neither implies I know enough nor does it make me infer that another user has sufficient information to make an informed decision about its use.

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And you did not read the page I posted so stop the argument now OK? Arguing the fact that its banned or not is pretty stupid IMHO. Use PPE Personal Protective Equipment to Protect yourself and look at that page I posted. Be a smart consumer. If you cannot find green MDF products in your area use PPE.

So now my keyboard is not working great. Keys are not working right on my laptop.