EXHIBIT 5.1

                             PHILLIPS & HADDAN LLP
                                Attorneys at Law
                        4675 MacArthur Court, Suite 710
                        Newport Beach, California 92660
                                 (714) 752-6100
                            Facsimile (714) 752-6161


                                October 10, 1997



Summa Industries
21250 Hawthorne Boulevard
Suite 500
Torrance, CA 90503

     Re:  Registration Statement on Form S-8
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Ladies and Gentlemen:

     In connection with the pending Registration Statement on Form S-8 (the
"Registration Statement") filed by our client, Summa Industries, a California
corporation (the "Company"), pertaining to the issuance and sale of up to an
aggregate of 400,000 shares of the Company's Common Stock (the "Shares")
issuable under the Calnetics Acquisition Stock Option Plan (the "Plan"), we have
been requested to provide our opinion as to certain legal matters regarding the
issuance of the Shares.

     For the purpose of rendering this opinion, we have made such legal and
factual examination and inquiries as we have deemed necessary or appropriate for
purposes of this opinion.  On the basis of such examination and inquiries, and
relying thereon, we are of the opinion that the Shares, when issued and sold
upon exercise of options granted and to be granted under the Plan on the terms
and conditions set forth therein, will be duly authorized and validly issued,
fully paid and nonassessable under the laws of the State of California.

     We hereby consent to the use of this opinion as an exhibit to the
Registration Statement and to the reference to us under Item 5 of Part II of the
Registration Statement.

                                    Very truly yours,

                                    PHILLIPS & HADDAN LLP



                                    By: /s/ James M. Phillips, Jr.
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                                        James M. Phillips, Jr.