Plywood or MDF for MFT Workbench Builds? JP's Vlog #4
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- čas přidán 20. 02. 2022
- Which material is best for the MFT workbench build? Plywood or MDF.
Finnish Birch Plywood booklet:
www.wisaplywood.com/siteasset...
In this video I compare Birch Plywood and MDF for suitable materials to construct your MFT work bench from. - Jak na to + styl
Excellent experiment! Some comments-
Moisture is the main cause of movement (thermal expansion of steel is very similar to MDF). With MDF the dimension increases with moisture, but does not fully return when it is removed (there are a couple of scientific papers measuring this effect).
This can happen differentially over the sheet, causing skewing as well as linear movement. So the dogholes are no longer at 90deg to each other.
The ply you showed looks like the normal 7 layer for 18mm- I was fortunate to obtain a sheet that was 13 layer; it is beautiful stuff!
MDF is much cheaper than good Baltic ply- but then an Aldi tracksaw is much cheaper than a Festool... and accuracy is a sum of the parts. The weakest link in the chain determines the accuracy of the result.
The published specification for Medite (a quality MDF) is for a linear stability of 0.3% - which is 3mm per metre. Cheaper may well be poorer...
Tightening tolerances always costs money, it depends on what is required for the result. Understanding the compromises involved avoids disappointment.
It is not always remembered that the original Festool MFT does not reference cuts to the dog-holes- they are for clamps. The cut is reverenced to the aluminium frame; and is adjustable for angle.
Keep up the good work!
Thanks Mike. I said a couple of times in the video, I hoped to forge a conversation because it is a subject we all have interest in - my wife said it is the most boring video I have ever made! Working for manufacturers over they years I have witnessed plenty product failures (and false claims) I am thrilled you have devoured the data sheets from manufacturers, my current job dictates I do the same. It is amazing what info is contained within. Regards JP.
@@Smallbarnworkshop It is a topic I have followed for a few years. There are scientific papers on the subject, but not easy to find. I spent several years designing equipment that needed to meet international standards, so I tend to question design choices... For me, relying on compressed wood fibres for measurements (such as cutting sheet goods square) seemed doubtful. Seeing the lengths CNC machines go to to achieve accuracy that is also claimed by some MFT users raised questions...
Working in the drywall arena our tolerance must seem huge compared to engineering . Add BS8212 to your reading list.
I think that I was one of those who were talking about expansion in MDF, plywood etc. firstly, however, another recommendation for problem-solving whilst walking the dogs; amazing how ideas and solutions come to mind whilst you’ve been occupied doing something else.
As you mention in another comment, the quality of the substrate could well be a significant factor. Our local B&Q often has quite large offcuts of their MDF left outside to be taken in exchange for a donation to their charity. I have taken some but only use it - would only ever use it - for sacrificial purposes. They also do have, on rare occasions, a product which is either wall or floor laminate and the core of this is very good quality such that I do use it for jigs.
As you and others have said, there is a lot of confusion about grades of plywood such that I only ever buy it from a merchant that I trust or when I personally have seen the product. The offcut you showed is what I would expect from first class plywood (I try never to describe something as birch plywood because that conveys the idea of quality which is sadly lacking in many products called birch plywood); the MDF seemed to be of the box store quality.
For relative newcomers, this is a minefield. If I can offer my thoughts - for MDF, buy only that made by Finsa, Kronos and Medite ( I think there is one other mentioned that I don’t recall); I do buy some very nice MDF-based products from Finsa such as their very high quality veneered sheets which is textured on one side. For plywood, try and ignore terms such as “Baltic” and go to a good merchant (not box store) and ask about what they stock. Buy from EBay etc. with caution - some say hardwood as if that were a sign of high quality in itself; it’s not. I don’t think the term hardwood in this context has any great significance - it’s about the lack of patched faults on at least one of the surfaces, the number of layers, the consistency of those layers and the absence of voids when you look at the edges.
We recently had a widespread shortage of sheet goods particularly during the pandemic. Prices shot up with OSB costing more than plywood. What resulted from this was a market vacuum into which lots of low grade product was sucked. If you had to, you bought some but that’s not the case anymore and, obviously, some suppliers still have stocks of this that they want to get rid off quickly. If the price seems too good to be true, then beware.
Morning Theo. It was your comments and the subsequent discussion that inspired this video. Caber is the other UK production.
It is a while since I was a timber salesman, we always needed a "fighting Brand" and your companies price of 18mm MDF became the benchmark of how your general pricing was judged. Most companies, therefore, stocked (usually) 2 of the 3 UK brands - that always leaves the door opening for negotiations with the other suppler and sometimes caused a reshuffle of stock for the following year. Then a budget range of MDF (chipboard flooring etc..) for those customers or projects, that needed to buy on price and not quality. This product was bought on the market as a forward order and may consist of a 1000 packs. the next 1000 packs came from somewhere else. If I remember correctly, the going rate for 18mm MDF (circa 1998) was £8 per sheet! I paid £11 for quarters of a sheet a few weeks ago!.
I know these usually end up in secondary merchants as they have an extra margin to be made and need to be affordable. Also, offering sheets cut to smaller sizes 4x 2, 6x2 etc realises extra margin as they can offer a service to customers that the bigger boys cannot serve.
I left for the drywall market in 2003 and have been here ever since. My knowledge of plywood / sheet materials work well for me here as we buy ply and OSB by the truck full.
Thanks for the idea of this video. Keep them coming :-)
Regards JP
@@Smallbarnworkshop thank you for your reply. I can only take partial credit - along with Mike (?). That discussion could branch off into what is accurate for woodworking; in fact, what is accurate for the hundreds of differing types of woodworking. There is no point in me working to the same tolerances for wall panelling as for piston-fit drawers (which I have always regarded as an affectation rather than necessity. There is knowledge to be gained as to how accurate do I need to be for this job/piece. Then how do I measure accuracy and how do it I mark it. On many occasions, the accuracy of a precision ruler doesn’t matter greatly so long as you use that ruler for every measurement; discrepancies occur when you switch between laser to tape to ruler to vernier gauge.
Marking that measurement is also a good habit to get into; I might use a carpenters pencil for exterior work but internally, I use a 2H mechanical pencil alongside a selection of Incra rulers and squares plus a 2B which I use to make the timber for face side, top, bottom etc.
Going back to piston fitting and the like. For a relatively short period of about 5 years, I started a small sideline business to my own much large concern making furniture for others. I had no intention of getting into cabinet making to sell on but I had some wealthy American clients of my main business who, when we talked about styles of furniture, asked if I would make them items in the style of Voysey, Morris, etc. We ended up making about 30 pieces in total for this circle of ex-pats and it was low turnover/high margin business. Anyway, I showed a design for a desk to the American wife of one of the group and explained about quarter sawn oak, styles of hardware etc. when she asked me about those arrow things in the sides of the drawers. She said that this detail detracted from the overall simplicity and honesty of most Arts and Crafts movement pieces. I had to agree and started to think about dovetails, piston fit drawers etc and came to the conclusion that mechanical jointing is no longer necessary (we have chemical jointing which is worlds away from what people like Chippendale could imagine; if he had had stuff like epoxy etc. would he have paid his workers to spend unnecessary time cutting dovetails?).
I suggest that the majority of dovetails and piston fit drawers are only there to please the person who made them; to prove how good he is; to be evidence to other woodworkers that he has skill. Just my thoughts.
A alot of fine wood working is there for aesthetic pleasure. Although the I admire those with the skill.
Joiners pencils are like a crayon and we sharpen out pencil with anything we have to had that resembles a blade 😂
Construction tolerances are huge compared to engineering. I work in a industry where +/- 5mm is spot on!
Thanks for the experiment. I was quite surprised.
Glad you liked it David. Regards JP
Thank you SO much for this. As a beginner, there are so many useful & fantastic YT videos on actually making stuff, but relatively little on expansion/contraction/tolerance. From what you've mentioned here and in your previous posts, you're obviously the UK oracle on this subject.
I'm still pondering the empirical notions of a) 'Square', and b) Movement.
Many fab YT woodworking sites are USA and deal in American Imperial measurements, there seems to be a lot of snobbery about thousands of an inch over even the smallest distance.
I'll be happy if my first build doesn't fall about like a clown's car and I still have all my fingers.
Cheers.
Thank you for your kind comments. Regards JP
If the material expanded and contracted in a linear manner, it would not matter for practical purposes. Sadly, the contraction does not match the expansion, so local areas of distortion can build up. This means the angles between features are liable to movement.
@@Tensquaremetreworkshop Thank you very much for your helpful clarification and further comments. Much for me to consider!
Gr8 analysis, it wud be great to see if this happened on moisture resistant mdf
Thanks for the comment and watching. I am going to re-do with other products including MR MDF. Regards JP
Intresting Video that, tbh wasn’t expecting mdf to shrink this much.
I was surprised that the softwood and MDF was about the same, especially along the grain. Thanks for watching. Regards JP
Interesting video apart from the movement I personally think plywood top are a lot harder wearing. But MDF is a lot cheaper to replace. Be interesting to try the same test with moisture resistant MDF
Hi Mark. I didn’t have an MR but I am going to redo with some. Regards JP
'moisture resistance' refers to the bonding agent- the fibres are the same, and it is they that absorb the moisture. Published data shows no real difference whit conventional MDF.
I have just had fitted an electric loft ladder by LOFTOMATIC and it is a wonderful addition to reducing my effort to get in the loft. Worth a look.
Thank you. I will take a look 👍
That looks way 😎
I just want to pose a question, to give perspective. It is the sort of question that I wish I had asked myself more often...
If you have spent several hundred pounds on a track-saw, rail, dogs, fence, etc plus a couple of hundred on a jig system for making dog holes, how important is it to get the cheapest material to use all of these on?
I have often regretted getting too cheap an item- I cannot recall regretting getting the best.
It is a great question Mike. I am drawn to gadgets and some of my kit is that...
Couple of points I can make.
1) Benches in general. I started work as a bench hand joiner. Pretty much the first thing you did was make a bench when you started at a company. These were made very quickly, and of spiked together 2 x 3 / 2 x 4's with a chipboard top and a lump of 2 x 8 to create a tool well. The quality of the bench was poor and did not reflect in anyway to MFT benches. From these we managed to make great quality joiner items for shops . pubs bars etc...
2) As a bench joiner we received a small amount of money (circa £1.60 per week) to buy and maintain our tools. The job was not particular well paid. It was amazing what quality joinery, some guys with cheap tools could produce. My tools were stolen just after I left the trade. I only ever replaced them when i needed something for a DIY project, with cheap tools. The tool kit I have now is the best I ever owned. The Festool was a dedicant purchase. The Bench dogs were my combined Birthday / Christmas present from the family.
Regards
JP
@@Smallbarnworkshop Yes, I too am a tool buff- sometimes buying stuff I cannot justify- at least to my wife.
It is certainly possible to create amazing product with rudimentary equipment- I have been priviliged to see goldsmiths create beautiful items using only a few hand tools and a wedge of wood sticking out of the bench. That is the nature of skill. Once we mechanize what we do (from simple jigs up to CNC machines) we are in the hands of the accuracy of the tooling. We become mechanics, operating machines that determine the outcome. What we gain is speed and consistency. Such things are a matter of choice, there is no right or wrong. But, whilst we can overcome imperfections in tools when used by hand, using skill, a machine depends on the design , accuracy, and quality that went into it. It is, by design, meant to eliminate the human factor. The need is to make it 'good enough' for the desired result. That varies widely, of course. If the product is going to move over time (like MDF) there is no point in obsessing about the tool producing it. Important, though, to understand the limitations if a different, more critical, item is to be produced. A good table saw will invariably have a cast iron table and motor mountings- to ensure that it will never be the weakest link. When we substitute MDF (or even good ply) we are losing some of that margin; it may be OK for what we are doing, but it is still limiting. Awareness of that is key.
@@Tensquaremetreworkshop all of this is extremely interesting and should be a thread that particularly newcomers to woodworking read. As I’ve said in another comment on this channel, I use a carpentry pencil if I’m working outside - visibility is more important than fine accuracy. When I’m stud framing our barn conversion) a greater accuracy is required and I’m usually happy with +/- 2mm. For work in my shop, which is now entirely for friends and family, I work from anything from +/-0.5mm to thousands of an inch ( which I measure by holding pieces up to a light and gauging with the use of a precision tooled straight edge.
Is this required? Not always; sometimes, the requirement is for 2 or more pieces to be the same as each other rather than exactly a given measurement; in that, I find the feel of a finger over the edges to be just the simplest way. I’m not sure that all the machines we have all got (table saw, band saw, router table, morticer, dominos, track saws etc. ) add to accuracy - but they make a job faster. I use dominos a fair deal on small items and, in theory both pieces should mate together with the face surface interface being smooth; mostly they do but I do find, no matter carefully I make the mortises, there is sometimes a discernible ridge between the 2. All of this comes down for me anyway that nothing is ready straight off the machine; you have to run test pieces through before and check your work after. I can’t remember any kind of assembly being perfect in all aspects straight out of the cramps. I use everything from chisels to abrasives to planing to card scrapers to finish the item off. Using the right material is critical for every reason from accuracy to aesthetics. I make a lot out of quarter sawn oak; it’s aesthetic is wonderful for me but the method of cutting means it’s more stable than anything crown cut. For panel work, I obviously use plywood or mdf but I’m very particular about the quality of those. For smaller pieces, I prefer to veneer myself; usually cutting my own veneers which are generally 2mm rather than the machine cut 0.5mm. My way gives more room for finessing the piece. If I’m making a wardrobe, then I will buy pre-veneered but, again, quality control is important. I’m lucky in that I can go and see what I’m buying before it’s put on the lorry; most can’t and I can only advise to buy from just a few places that you learn to trust and understand that cost and quality rise and fall together.
So, back to machines. I’m now 67 and my body complains every day. So machines like a domino help me to lessen the physical effort but I don’t assume final accuracy. They also add speed (the set up time for a domino is a fraction of that for a mortise and tenon). That speed is critical to those trying to make a living but not a great concern to me.
It’s an old argument as to whether the most expensive brands mean better tools. I’ve found that the answer is no; not always but sometimes. I wish it were simpler for newcomers; so many might buy Festool because of the name. Experience tell me that some of the Festool range is average in performance ( for me drills and planers) whilst others are very good (routers). I guess that the only advice I could give is to read and watch a lot - that kind of resource wasnt there 20,30, 40 years ago.
Your thoughts on this would be greatly appreciated.
@@theofarmmanager267 I am in agreement with all of the above. My point was, largely, that the weakest link tends to set the accuracy. So, for each item, we have to ask if they are 'letting down' the other parts in the process. It seems an extreme case for woodworkers to move from cast iron tables on table saws to MDF as the surface on which to cut wood. Yes, it can all be corrected by hand afterwards, but the idea is to avoid that. Cast iron is preferred to an aluminium casting, as it is more stable and can be ground to high accuracy. Which will remain for decades. Anyone who has leaned a sheet of MDF against the wall, to come back to a banana knows that it can only loosely be described as stable. Again, if it meets the accuracy that the task demands, fine. But we can all admire items that exceed 'fitness for purpose'. An AK47 is very fit for purpose at minimum cost- but a Purdy shotgun exudes quality that has, for most people, a value in itself.
@@Tensquaremetreworkshop I’m in broad agreement with you. However I see (good quality) MDF as excellent where it’s properties are known and understood. I wouldn’t use even the best MDF as a wide shelf unless it is strengthened front, back and middle. I haven’t got the sag table with me but if MDF bends under 100kgs over 1000mm ( just figures) then plywood bends roughly under 200kgs. Where I have wanted chunky shelves - perhaps in the style of Greene and Greene - then I’m happy with MDF with front, middle and back support underneath. I have such pieces that I built 20 years ago as part of a book cabinet, and they are as straight as they should be.
MDF will bend when lent at an angle against a wall; plasterboard and OSB bend even more easily; plywood less so; the cheap end of the softwood market deforms easily. I think it is about giving people the information of what to use and when. When I’m jointing the face of a piece of hardwood (oak, cherry, walnut, sycamore) I know that the resulting “flat face” isn’t perfectly flat. I would then run the other face through the thicknesser and then run the first face through the thicknesser; it doesn’t result in either face being “flat” but probably parallel to each other. I have a large cast iron table on my 12”table saw; before each set of cuts, I measure the angle between the blade and the bed to make sure it is the 90 degrees or 45 or whatever I need; I measure both with an igaging digital block and putting up my test square (from Woodpeckers and never used for anything else). Is it exactly the 90 degrees? I doubt it is every time, it may well be 90.1 or 89.9 but, practically, that matters little or none.
There are degrees of accuracy that different applications demand and that’s a learning curve that most people have to go through. There is a use and limitations for most materials and that’s a second learning curve. I would start with the first point of possible inaccuracy and that is the measuring and marking out. I’m less worried about the materials because I hope I’ve learned most about what might happen to it.
As an update, I have conducted some accurate measurements on my own (birch ply) table, and put the results in czcams.com/video/woG1U2qbRWE/video.html
They would indicate that ply is, indeed, more stable that MDF (comparing my results with those you obtained here) but there are other issues that apply...
Mike, just watched. Thanks for sharing. Regards JP
@@Smallbarnworkshop I intend repeating over time. If I can get hold of some MDF I will test that also...
Probably the only saving grace of the movement is that all the dog holes should move the same amount? So if your fence is square when you drill the initial MFT holes it should still be square after the expansion/contraction. Or maybe I'm blowing smoke out of my ar**? 😂
Ian. I agree ☝️ I have never experience the holes swelling so the dogs do not fit so that’s good. 1.5mm I’ve r almost a metre is next to nothing I’m woodworking terms. Regards JP
Sadly not. Because MDF does not fully return after a moisture cycle, and differential absorption can happen (sheltered areas of the table from mounting etc) one cannot rely on the table remaining square.
Ice cream melts, concrete cracks and wood moves.
Absolutely, but not all woods are equal. Regards JP
I don’t make fine furniture from ply or MDF and for those things I build with either, who cares?
Poor dog
this might be an interesting video, but I just can't watch it - that background music is so annoying..there is no need for it
Sorry you don’t like it but that’s how we roll around here.