By Steve Broad - 10/17/2017 9:45:59 AM
I would like to make a one piece mould (less work) of the front of my Elan so I can make a one piece flip front. The bonnet will be fitted and blended in prior to making the mould. I can't see any locks. The mould should flex around the wheel arch lips. Can anyone see any problems?
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By oekmont - 10/20/2017 10:13:15 AM
I never said titanium is hard. I said is hard (difficult) to work with. At least compared to regular steel or aluminium.
Hardness and tensile strength are all most proportional. Both characterise the resistance against (fatal) ductile deformation. Source: 3 semesters of material science at the university.
Grade 5 titanium has a tensile strength of about 900N/mm^2 and therefore is less tough (And hard) than an 10.9 steel screw (first number x100= Rm).
The problem however ist it's low thermal conductivity and a specialc chip shearing. Source: 1 semester of "chipping technology with geometrical defined edges".
This leads to thermal stress for your drill (carbide ones have a much higher heat tolerance, but are more vulnerable to thermal shock than hss ones) and a problem with the removal of the cut off material. This means you should drill only a short distance, then remove the chips out of the hole. For initial drilling, carbide drills are not recommended (but the hobbyist usually don't have any either), as they tend to break because of the stuck chips. But if you are planning in drilling much in ti, a secondary carbide drill to get to the final diameter could pay of.
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