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  1. #1
    Join Date
    Jun 2020
    Location
    Geelong
    Posts
    21

    Default Camelback straight edge

    Hey guys

    I am in need of a straight edge, as for some reason I have developed a predilection for buying worn out old machines. I tell people that collecting these old machines is a hobby, but deep down I wonder if its not really an illness. Whatever the case, these machines need reconditioning.

    I did have a good look around, and you can buy some pretty nice castings from the US but by the time you pay for shipping on a 1200mm (or 48") cast iron lump the price is unreasonable. I emailed Dennis over at PM, who makes the featherweight castings and unfortunately by the time it reaches AUS it would have been somewhere around $1200.

    I thought surely we can make something similar in Australia for a reasonable price, so I reached out to a local foundry and got a surprisingly good result. The quote I got from them was for stress relieved grey cast iron, grade 2p/T260, and I will make and supply the pattern to keep costs down. I think it will cost somewhere around $650. The price went down the more I could order.

    I have attached a few screenshots of the design, which I made similar to photos of old B&S models I have seen in photos. Specs are 1200mm long, the sole is 65mm wide 25mm high and includes a 60 degree bevel. F360 reckons as modeled it will be 22kg - my initial drawing had it at 18kg but the foundry guys asked me to increase the thickness of the web and the perimeter band, which drove it up considerably.

    I know weight is a big concern for some people. It always gets brought up when these things are discussed. Checking the specs on other manufacturers offerings, this one occupies the middle ground between the lightest and the heaviest. And although I would like to make it lighter, I have to take the foundries advice regarding the dimensions, as they know what they are capable of.

    I figured if I need one maybe you guys do too. Let me know if you want one and when I am ready to take it to the foundry I will let you know the final costs given how much interest there is.

    Cheers, Rowdy



    1200SEREV4 1.jpg1200SEREV4 2.jpg1200SEREV4 3.jpg

  2. #2
    Join Date
    Sep 2009
    Location
    Newcastle
    Posts
    260

    Default

    I would have been interested, however I acquired a 48" a couple of weeks ago.

    22kg sounds very light. Not sure what mine weighs but it is a solid lift.

    Some on mine is 73mm wide (no dovetail, square edged).

    You don't have any lateral ribs on your design. Most I've seen do and mine does

  3. #3
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    33
    Posts
    1,367

    Default

    Just to be aware. SG (spheroidal graphite) iron is most common in castings these days and its a fair bit tougher to scrape. I did a 1m SG straightedge and it was a fair old slog.

    Sent from my SM-G973F using Tapatalk

  4. #4
    Join Date
    Jun 2020
    Location
    Geelong
    Posts
    21

    Default

    Re. the iron grade, speaking with the foundry I explained that it is most important that the material be easy to work. These will be cast in Grey 2P, not ductile 3D (Spheroidal Graphite) cast iron.

    Cast Iron - Interlloy

    ^^Not the place that is doing the work, but a handy reference.

    my understanding is that 2P/T260 is our equivalent to grade 40 which is what is commonly used elsewhere for this application.

    re. the lateral ribs, I didn't think it would need them as the web is 12mm thick, and the base of the sole only protrudes a maximum of 31.5mm from the web on the beveled side, less on the square side.

    I did buy some half round moldings that I will use in lieu of ribs on the pattern if it looks like it needs them. I thought getting the right draft on all the ribs looked too much like hard work as well. The half round moldings have natural draft.


    Cheers, Rowdy

  5. #5
    Join Date
    Sep 2009
    Location
    Newcastle
    Posts
    260

    Default

    My straight edge:
    1232mm long

    Base is 73mm wide, 22.3mm thick

    Spine is 15.7mm thick
    There is a top along the spine - 53.3mm wide, 16mm thick.
    Highest point is 212mm from spotting surface to peak of camelback.

    There are ribs running from the edge of the spine top to the base - 14.2mm thick.

    SE.jpg

    I made a rough CAD model. Solidworks reckons it weighs about 38kg without the feet on the back of the camel back.
    It feels like a 35-40kg lift.

  6. #6
    Join Date
    Jun 2020
    Location
    Geelong
    Posts
    21

    Default

    That is a really nice looking SE, Pippin. Bloody heavy duty! The feet are a handy addition i should add to mine.

  7. #7
    Join Date
    Jun 2020
    Location
    Geelong
    Posts
    21

    Default

    I dont know where my post went from this morning, but here goes again;

    re. the grade of iron I have specified 2P/ T260, not 3D/ SG. This is a common grey cast iron, from what I understand its the Aussie equivalent of grade 40 which people use in this application in the states.

    Cast Iron - Interlloy - a handy reference.

    re. the ribs on the webbing, I didn't think it would need it as the web is 12mm thick and the furthest the sole protrudes from the web is 31.5mm. I did buy a length of 10mm half round molding which I was going to use in lieu of ribs. making the ribs and adding draft to all of them seemed like to much work. the half round shape has natural draft.

    A few more pictures from this afternoon. Wood working is not my usual lark but I have a few handy tools acquired over the years. All of this was done with some string, a power planer, a ryobi jigsaw, a ryobi saw/router bench, and a makita 1/4"router, which I made an adaptor for to fit it to the ryobi bench. And plenty of sanding! I am pretty happy with the results so far.

    Cheers, Rowdy

    IMG_2531.jpgIMG_2532.jpgIMG_2536.jpg

  8. #8
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    33
    Posts
    1,367

    Default

    The only other thing I would add is a flat spot on the top for popping your level on.

    Sent from my SM-G973F using Tapatalk

  9. #9
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    55
    Posts
    1,843

    Default

    Out of interest, if you池e planning to use the old CMM granite table to scrape in the straightedge have you checked how flat it is?

    Steve

  10. #10
    Join Date
    Aug 2009
    Location
    Lara, Vic, Oz
    Posts
    40

    Default

    Hi Rowdy
    Whilst not looking for such a large camelback, a year ago I was looking to get quotes for more simple shapes cast locally, such as lathe backplates (~200mm) and lapping discs etc. Then CV19 kicked in and I didn't follow up. Any idea whether simpler shapes (discs/doughnuts) could be cast alongside the more intricate ones, packing the mould space and helping economics? Or is cost based on kg poured, for example?
    Cheers
    Si

  11. #11
    Join Date
    Jun 2020
    Location
    Geelong
    Posts
    21

    Default

    Re. The cmm table, i have absolutely no idea how flat it is. It was used for checking flywheels at the old ford factory. There was a large jig bolted to the table with fixtures for checking the flywheels in different orientations. This took up half the table and the other half looks like it was used for the printer to print of the test reports.
    Given its use i imagine it probably has little wear but i wont know until i move it to its final location, level it, clean it properly and then check it. Iツ値l be checking it myself with some precision levels and an indicator. While I was dropping of some meters for a calibration, I did enquire as to the cost of getting it done professionally and the guy quoted 1600 of the top of his head. That was just to check its condition- no lapping.
    While it may end up being out of spec, given how big it is i was willing to take the chance i could find a flat spot on it. Not an expensive gamble at $89, either!

    2F21E805-052F-4F3E-9A31-D406B6A29CB9.jpg


    Re. The casting costs, its definately not just the metal poured as the guy was talking about a sand- metal ratio, thats why i am getting two done initially. There will be two in the sand sole-sole with the sprue in between.
    I dont think it would be worth getting a backplate cast, imo. You can buy cast iron rounds by the mm basically, and easily up to 200mm. I made one last year for my last lathe resto, a prettt old but large german made Alfred Erikson. I bought a new 4 jaw for it and machined a backplate to suit. I cant remember how much it was, but for a 40mm slice of ~180mm 2p grey cast iron it wasnt expensive. Iツ壇 say definitely cheaper than getting one cast.


    I got it from Surman metals in SA, they freight aus wide. I was over there at the time and brought two slices back with me on the plane lol but i have had dura bar sent to me before and it was a reasonable price.

    C58A15F4-0B11-4239-A8AB-0E54134D30EF.jpg42B5A229-CA9B-4428-8B92-FB685265B49D.jpg

    Today i made some little jigs to hold the web on the SE while the glue dries. Tomorrow iツ値l start on the perimeter band. This is probably the longest wood work project i have done in 15 years. Usually im just knocking out a stool or a set of steps or something. This seems to be taking forever!

  12. #12
    Join Date
    Jun 2020
    Location
    Geelong
    Posts
    21

  13. #13
    Join Date
    Jun 2011
    Location
    Australia east coast
    Age
    68
    Posts
    2,646

    Default

    Quote Originally Posted by qb6sagr View Post
    Hey guys

    I am in need of a straight edge, as for some reason I have developed a predilection for buying worn out old machines. I tell people that collecting these old machines is a hobby, but deep down I wonder if its not really an illness. Whatever the case, these machines need reconditioning.

    I did have a good look around, and you can buy some pretty nice castings from the US but by the time you pay for shipping on a 1200mm (or 48") cast iron lump the price is unreasonable. I emailed Dennis over at PM, who makes the featherweight castings and unfortunately by the time it reaches AUS it would have been somewhere around $1200.

    I thought surely we can make something similar in Australia for a reasonable price, so I reached out to a local foundry and got a surprisingly good result. The quote I got from them was for stress relieved grey cast iron, grade 2p/T260, and I will make and supply the pattern to keep costs down. I think it will cost somewhere around $650. The price went down the more I could order.

    I have attached a few screenshots of the design, which I made similar to photos of old B&S models I have seen in photos. Specs are 1200mm long, the sole is 65mm wide 25mm high and includes a 60 degree bevel. F360 reckons as modeled it will be 22kg - my initial drawing had it at 18kg but the foundry guys asked me to increase the thickness of the web and the perimeter band, which drove it up considerably.

    I know weight is a big concern for some people. It always gets brought up when these things are discussed. Checking the specs on other manufacturers offerings, this one occupies the middle ground between the lightest and the heaviest. And although I would like to make it lighter, I have to take the foundries advice regarding the dimensions, as they know what they are capable of.

    I figured if I need one maybe you guys do too. Let me know if you want one and when I am ready to take it to the foundry I will let you know the final costs given how much interest there is.

    Cheers, Rowdy



    1200SEREV4 1.jpg1200SEREV4 2.jpg1200SEREV4 3.jpg
    I can do parallel flange ones 1m long for half that price. I think I still have 2 under the surface plate that I've machined. Not dovetail though I did machine one edge to 45 deg.

    Personally I don't like the camelback types. Aesthetically they're nice and maybe they do end up a bit lighter for the length but I had an engineer friend do FEA on my design and the sag was in the order of a couple microns with it only supported on the ends. My care factor was even less.

    Casting isn't cheap in Australia that's for sure. I've been toying with making a new & improved pattern and getting some more 640mm dovetail ones cast but the round tuit for that job is way back in the queue behind the boat work.

    PDW

  14. #14
    Join Date
    Mar 2014
    Location
    South of Adelaide
    Posts
    918

    Default

    Quote Originally Posted by qb6sagr View Post
    Re. The cmm table, i have absolutely no idea how flat it is. It was used for checking flywheels at the old ford factory. There was a large jig bolted to the table with fixtures for checking the flywheels in different orientations. This took up half the table and the other half looks like it was used for the printer to print of the test reports.
    Given its use i imagine it probably has little wear but i wont know until i move it to its final location, level it, clean it properly and then check it. Iツ値l be checking it myself with some precision levels and an indicator. While I was dropping of some meters for a calibration, I did enquire as to the cost of getting it done professionally and the guy quoted 1600 of the top of his head. That was just to check its condition- no lapping.
    While it may end up being out of spec, given how big it is i was willing to take the chance i could find a flat spot on it. Not an expensive gamble at $89, either!

    2F21E805-052F-4F3E-9A31-D406B6A29CB9.jpg


    Re. The casting costs, its definately not just the metal poured as the guy was talking about a sand- metal ratio, thats why i am getting two done initially. There will be two in the sand sole-sole with the sprue in between.
    I dont think it would be worth getting a backplate cast, imo. You can buy cast iron rounds by the mm basically, and easily up to 200mm. I made one last year for my last lathe resto, a prettt old but large german made Alfred Erikson. I bought a new 4 jaw for it and machined a backplate to suit. I cant remember how much it was, but for a 40mm slice of ~180mm 2p grey cast iron it wasnt expensive. Iツ壇 say definitely cheaper than getting one cast.


    I got it from Surman metals in SA, they freight aus wide. I was over there at the time and brought two slices back with me on the plane lol but i have had dura bar sent to me before and it was a reasonable price.

    C58A15F4-0B11-4239-A8AB-0E54134D30EF.jpg42B5A229-CA9B-4428-8B92-FB685265B49D.jpg

    Today i made some little jigs to hold the web on the SE while the glue dries. Tomorrow iツ値l start on the perimeter band. This is probably the longest wood work project i have done in 15 years. Usually im just knocking out a stool or a set of steps or something. This seems to be taking forever!

    good buy with that lump of granite. Was that the Cmm that still had the probe on it?

  15. #15
    Join Date
    Jun 2020
    Location
    Geelong
    Posts
    21

    Default

    Quote Originally Posted by PDW View Post
    I can do parallel flange ones 1m long for half that price. I think I still have 2 under the surface plate that I've machined. Not dovetail though I did machine one edge to 45 deg.

    Personally I don't like the camelback types. Aesthetically they're nice and maybe they do end up a bit lighter for the length but I had an engineer friend do FEA on my design and the sag was in the order of a couple microns with it only supported on the ends. My care factor was even less.

    Casting isn't cheap in Australia that's for sure. I've been toying with making a new & improved pattern and getting some more 640mm dovetail ones cast but the round tuit for that job is way back in the queue behind the boat work.

    PDW
    can you post a picture of your SE? I壇 be interested in buying one if its half the price, as you say.

    I dont think the camelback is strictly necessary at this length, it really is an aesthetic choice of mine to go with it. I think if you go much bigger, and if you intend to lift it without assistance, you have to use a camelback design.

    I was pretty happy with the price they gave me. I dont have any experience in getting things cast or in dealing with foundries, so maybe it is expensive. I was just comparing the price they gave me to the cost of a SE as advertised in the states. And i was prepared to pay a bit more to get something made locally. I definitely didnt want to get one from one of the chinese or indian mobs, even though im sure the product they sell is probably ok. I just think why buy from overseas when we can do it ourselves for a similar price.

    Rowdy

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