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How Many Hinges Per Door?9/16
I need to bore a number of 3/4" melamine doors 14"W x 88"T, just not sure on the number of hinges. I'll be using Salice concealed hinges, and the literature calls for 5" for doors over 84", but in looking at these doors I'm thinking 4 would be sufficient, and I'd rather do 4 so the middle one doesn't interfere with the middle shelf in the cabinet. There's also a weight table in the literature, going by that it looks like fewer than 5 works. Which table should I go by? Thanks 9/17
In my experience, you will be okay with 4. The chart i used was for up to 24" wide doors. I converted the increment breaks to square footage. I calculated the different door sizes to make that decision. Wider doors undergo more leverage forces, necessitating more hinges. This served me well for many years, on 3/4 particleboard or mdf. Looking forward to what Dennis may offer, 9/17
Bernie, Your door size and weight puts it between the range for 4 and 5 hinges. The size puts it close to 5 hinges but still within the range for 4. Four hinges are acceptable. The number of hinges to use is actually based on a curve. As the weight increases and the door height increases the number of hinges required is determined by a point on the curve until the next level is reached. Using a weight of 2.5lbs per square foot for particle board/melamine, your door would weigh in at 22.5 lbs. As the height increases to 88” it would put you in the high end of the 4 hinge range. If the size remained the same but the weight was, say 35 lbs then 1 additional hinge would be recommended. See the chart below. Keep in mind, if the door has a long bar pull, it could add enough weight to change the number of hinges required. Hi Rich, how's everything in Chicagoland?
9/17
Dennis,
9/17
Al, Although hardwood will vary in weight from species to species, I normally use 2.7lbs/sft as an average. Based on this and your door size, 2 hinges would be sufficient. (19 X 36)/144 = 4.75 Sqft.
Below is a door weight calculator based on the material and a simplified chart from the Salice catalog used to determine the number of hinges to use.
9/17
Thanks always Dennis. 9/17
Bernie, I used the wrong square foot weight in calculating your door weight. Particle board/melamine would actually weigh 3.0 pounds per square foot. This would make your door 25 pounds. The answer, 4 hinges would not change. That's what I get for trying to think at 5:00am.... before coffee!!! 9/17
Thanks very much. 9/17
Dennis, awesome that you posted these charts. Makes sense the real issue is weight since that is what affects leverage even more than door width. Important to note hinge location affects it too. The closer to the top and bottom of the door, the better. Learned this the hard way. We are having some August weather here in the middle of September. Busy organizing the world here! 9/18
Well, I just got an email from sugatsune. They apparently just came out with a cup hinge that is meant for heavy doors. They claim 2 of theirs is equal to 5 of others. Doesn't look soft close though. BOOOOOOO sugatsune! 9/18
Sugatsune is a great company for specialty items. I recommend them all the time. They are the only supplier I know that offers stainless steel concealed hinges. I get requests for stainless steel hinges frequently, especially for cabinetry in MRI rooms in hospitals, for outdoor kitchens and for marine use. I always refer the customer to Sugatsune for these. According to the information in the Sugatsune catalog, 2 hinges are suitable for a maximum door weight of 55lbs. This indeed is a higher claim than most. Salice is 20lbs for 2 hinges. Blum specifies 15lbs for 2 hinges. (See chart below). The Sugatsune specs however call for the use of six #10 screws to fix the hinge and plate (compared to four #6 screws for Salice and Blum). The additional screws and their oversize would increase the load rating possibility. The cup depth is 15mm and it is a 94 degree opening hinge. I am sure this is a fine product as is everything I have seen from Sugatsune.
11/15
In the #3 answer by Denis Bean he posted a chart to calculate the number of hinges for the weight of the door. The chart has metric 120 = 22.5 lbs. I can't for the life of me find anything metric that will give me the same results, not even close. I'm doing something wrong for sure, can you set me straight so i can use the chart accurately?
11/16
Mike, My error, sorry. Actually the engineering chart was originally in "newtons". My error was in the conversion. Actually 22.5lbs = 100 newtons (not 120). (4.45n = 1 lb.). I used an online auto conversion that gave the answer "120n" = 22.5lb. I should have double checked it.  the measure twice, cut once rule. The number of hinges would remain the same however. 11/16
Thank you Dennis, i never heard of newton before this. I'm glad i can use the chart correctly now. If you don't mind i would like your input on the 165 degree hinge. I want to use it for an inset application with a thicker than normal door about 1 inch to 11/8 thickness. How small can i get the reveal between the door and cabinet side?
11/17
Mike, I agree that the 2 formulas seem to fight each other. Over the years, some Salice publications have presented the solution by solving for a negative number (the gap between the door and the side can be viewed as a “negative overlay”). I have always found this confusing. Note: These formulas hold true for only Salice hinges. Other brands have a constant (2) that is different and therefore will result in a different solution. I prefer Method 2 where you solve for the mounting plate height. It makes much more sense than having a negative number as the answer.
A = Gap
Method I: A = (2 + K)  H 2mm = (2 + 6mm)  6mm
Results: Gap = 2mm; Edge bore distance = 6mm; Mounting plate height = 6mm Method II: H = (2 + K) + A Here, you arbitrarily set the gap that you would like to see then solve for the mounting plate height that will give that desired gap between the door edge and the cabinet side. The edge bore distance is determined by trial & error until the formula balances. H = (2 + 6mm) + 2mm
Results: Gap = 2mm; Edge bore distance = 6mm; Mounting plate height = 6mm Now, as far as the amount of gap you will need to turn a door that is 1” (25.4mm) or 11/8” (28mm) thick using the 165 degree hinge, here is a chart showing the minimum gap required to turn a door of various thicknesses without interference. Take note that as the edge bore distance (K) increases, the amount of gap required decreases. You can play around with the numbers to get exactly the outcome you would like. This explanation is in context to your application being frameless or face frame with the side built flush to the edge of the frame.
6/29
HI....I have a shutter sized 20" wide and 13" height. What would be the recommended number of Auto hinges and the distance in between...Why I am asking is because in every chart it says that the distance between them should be greater than the width of the shutter. Kindly help! 6/29
Arism, The rule of spacing of the hinges is very important. I would not recommend hinging a door on the side that is only 13" tall and 20" wide using European concealed hinges. Can you hinge it at the top and make it a liftup door (shutter)?
11/5
Dennis, On the example of the original door that was 88" tall, wouldn't that convert to 2235mm (88x25.4) which would put it into the range of 5 hinges, instead of 4? 11/5
Bernie, You are correct it is close to 5 hinges and I would normally recommend this. Since you mentioned that the center hinge would interfere with a shelf and that the range is still within 4 (high end) I believe you are safe with 4. Also, it is quite a narrow door which gives you some breathing room too.
11/5
Thanks Dennis, I just wanted to make sure I was doing the conversion right. The charts are great, thanks so much for posting them.
